Actually, you use some "creative syntax" in your code, so no wonder it fails...
Among other things:
- You mix uppercase and lowercase letters: Java is case sensitive, you have to care about these case!
Examples: CreateFont should be createFont, SensorReading String = ""; isn't legal because String is a class name (BTW, we don't know either what SensorReading is), and you use a sensorReading type later. Idem for WriteText(), probably.
- A line like:
sensorReading myPort.readStringUntil = ('\ n')
doesn't make sense at all. (What this = is doing here?)
- You forgot to put semi-colons at the end of most lines of code
- The line
CreateWriter output = ("C: \ Users (x86) / alunosdefi / Desktop / data.txt")
is very strange too, and the spaces inside the path is going to bite you soon...

I suppose you are trying to imitate some code you saw, which is a good way to learn (if you understand what you are doing...). But take care of copying the code as it is, without interpreting it.

Suggestion: walk before you run. Look at the tutorials to make simple graphical sketches, it will give you a sense of what the language looks and feels...
And build your sketch progressively: type a few lines, run it to check the syntax and the logic, then adds a little more features, and so on.

BTW, I edited your subject line, because all caps subjects looks like you are yelling, which isn't appreciated here.

You may try to use separate threads for each timer.
Take a look at this simple sample and try to adapt it to your program:

final static int LINGER1 = 3  * 60*1000; // 3  minutes delay
final static int LINGER2 = 15 * 60*1000; // 15 minutes delay

boolean isActive = true;

void setup() {
  size(300, 200);
  frameRate(1);
  textSize(2 << 5);
  textAlign(CENTER, CENTER);

  thread("timer1");
  thread("timer2");
}

void draw() {
  background(0);

  final int m = millis();
  text(m/1000/60 + "\n" + m/1000, width >> 1, height >> 1);
}

void timer1() {
  while (isActive) {
    println("Action 1 done @ " + millis() / 1000/60 + " minutes!");
    delay(LINGER1);
  }
}

void timer2() {
  while (isActive) {
    println("Action 2 done @ " + millis() / 1000/60 + " minutes!");
    delay(LINGER2);
  }
}

the code is for Arduino or Processing??

In Processing i use this code:

1. if(second()==0 || second()==15 || second()==30 || second()==45){
2.   output.println(year() + "/" + month() + "/" + day() + "\t" + hour() + ":" + minute() + ":" + second() + "\t" + sensorReading); // Escrever Data/Tempo e Tensao
3.   }
4.   output.flush(); // Escreve todos os dados no ficheiro
5.  writeText("Valores: " + sensorReading);

and this is the result in notepad:

2013/7/22    17:51:30    Temperature= 23.03 || Temp min= 22.92 || Temp max= 23.29
2013/7/22    17:51:45    Temperature= 22.70 || Temp min= 22.70 || Temp max= 23.29
2013/7/22    17:52:0    Temperature= 22.42 || Temp min= 22.41 || Temp max= 23.29
2013/7/22    17:52:15    Temperature= 22.34 || Temp min= 22.32 || Temp max= 23.29
2013/7/22    17:52:30    Temperature= 21.98 || Temp min= 21.98 || Temp max= 23.29
2013/7/22    17:52:45    Temperature= 21.86 || Temp min= 21.81 || Temp max= 23.29
2013/7/22    17:53:0    Temperature= 21.85 || Temp min= 21.76 || Temp max= 23.29
......

This is my new code in Arduino:

1. PinAnalogA0 int = 0;
   valAnalog float = 0; / / Put the pin A0 to 0
   redPin int = 13; / / Red LED - Port 13
   yellowPin int = 12; / / Red LED - Port 12
   greenPin int = 11; / / Red LED - Port 11
   
   float temp = 0; / / Variable voltage to zero
   float maxi = 0, mini = 1000000 / / Set min and max value
   
   void setup () / / function executed only once, and preparation
   {
     Serial.begin (9600) / / opens serial port, sets the baud rate to 9600 bps
     
       pinMode (redPin, OUTPUT); / / Output Red LED
       pinMode (yellowPin, OUTPUT); / / Yellow LED Output
       pinMode (greenPin, OUTPUT); / / Output LED Green
   }
   
   void loop () / / Code to be executed - reading inputs causing Outings
   {
    
       valAnalog = analogRead (PinAnalogA0) / / Read the Arduino Analog Pin - A0
       temp = (valAnalog * 5.0) / 1024 / / Reading the value of voltage = 5V value * / 1024 bytes
       
       temp = 0.0201*(temp * temp * temp) + 0.301 * (temp * temp)+ 2.3*temp +  17 / / Convert the voltage to the value of the temperature
       
       if (temp> maxi)
       {
         maxi = temp;
       } / / Maximum temperature records
       
       if (temp <mini)
       {
         mini = temp;
       } / / Recorded minimum temperature
   
       if (temp> 32.0)
       {
         digitalWrite (redPin, HIGH) / / puts Red LED ON
         digitalWrite (greenPin, LOW);
         digitalWrite (yellowPin, LOW);
       }
      
       if (temp <= 23.0)
       {
         digitalWrite (yellowPin, HIGH) / / Puts Yellow LED ON
         digitalWrite (redPin, LOW);
         digitalWrite (greenPin, LOW);
       }
   
       if (temp> 23.0 && temp <= 32.0)
       {
         digitalWrite (greenPin, HIGH) / / Puts the Green LED ON
         digitalWrite (redPin, LOW);
         digitalWrite (yellowPin, LOW);
       }
    
       Serial.print ("Temperature =");
       Serial.print (temp);
       Serial.print ("| | = min Temp");
       Serial.print (mini);
       Serial.print ("| | Max Temp =");
       Serial.print (maxi);
       Serial.println ("");
     
       delay (1000);
   
   }

In Arduino, I'm showing the temperature in 1 in 1 second - delay (1000);

Here in Processing, I just show and record the readings in seconds 0, 15, 30 and 45, every minute!

I am also display a window printed on the temperature Arduino 1 within 1 second, that is, the temperature measured at the moment!

Processing here be possible to make one cycle to read the temperature of 6 in 6 seconds and 30 record the same in 30 seconds, keeping the temperature window to show the current temperature with 1 in 1 minute?

Perhaps using a code like this:

1. / / Int samples [5];
2. / / For (i = 0, i <4; i + +)
3. / / {/ / Get 5 samples temperature
4. / / Samples [i] = sensorReading???
5. / / SerialRead SensorReading + = samples [i];
6. / / Delay (30000)? (6segundos * 5 samples = 30 seconds)
7. / /}
8. / / = SensorReading sensorReading / 5; Calculates the average of 5 readings taken at the end of 30 seconds

Please, HELP!!!