You have to look at the Typography section of the Reference. Particularly createFont, textFont and text function.

looking at the  text examples should have answered all your questions... anyway, here it is...



PImage mapImage;
Table locationTable;
Table connTable;
int rowCount;
int transCount;
int x1, x2, y1, y2;
int mapWidth = 600;
int mapHeight = 563;
boolean reFresh = false;
PFont myFont;

String[] Locs = new String[mapWidth * mapHeight];


void setup() {
 size(mapWidth, 563);
 rectMode(CORNER);
  myFont = createFont("Arial", 14);
 textFont(myFont);
 mapImage = loadImage("europe_plastic.png");
 //Make a data table from a file that contains
 //the coordinates of each country.
 locationTable = new Table("locations20072009.tsv");
 connTable = new Table("conns20072009.tsv");
 // The row count will be used a lot, so store it globally.
 rowCount = locationTable.getRowCount();
 transCount = connTable.getRowCount();
 
 print("tranfers ="+transCount);
 
 for (int L = 0; L < (mapWidth * mapHeight); L++) {
   Locs[L] ="                ";  // clear out array
 }
 

}



void draw() {
   
   if ( reFresh == false){
     drawMap();
     reFresh = true;
   }
   
   if (Locs[(mouseY * mapWidth)+ mouseX].equals("                ") == false){
     //print("Location ="+ Locs[(mouseY * mapWidth)+ mouseX] + "\n");

      noStroke();
      fill(255);
      rect(0,0,230,30);
      fill(0);
      text("Location: "+ Locs[(mouseY * mapWidth)+ mouseX] + "\n", 10,20);
 }

 }








 
void drawMap() {
   
   background(255);
   image(mapImage, 0, 0);
   
   //line(168, 335, 153, 312);
   
   //Drawing attributes for the ellipses.
   smooth();
   fill(192, 0, 0);
   //noStroke();
   
   // Loop through the rows of the locations file and draw the points.
   for (int row = 0; row < rowCount; row++) {
     int x = locationTable.getInt(row, 1);  // column 1
     int y = locationTable.getInt(row, 2);  // column 2
     
     
     // instead of a single point, make this a square 5 pix high x 5 pix wide
     Locs[(mapWidth*y)+x] = locationTable.getString(row, 0);  // column 0
     
     Locs[(mapWidth*y)+x-1] = locationTable.getString(row, 0);
     Locs[(mapWidth*y)+x+1] = locationTable.getString(row, 0);
     Locs[(mapWidth*(y-1))+x] = locationTable.getString(row, 0);
     //Locs[(mapWidth*(y+1))+x] = locationTable.getString(row, 0);
     
     // add loop writing Locs[(mapWidth*y)+x] = locationTable.getString(row, 0) to each cell in array
     
     ellipse(x, y, 5, 5);
     
   }
   
   
 
 
   // Loop through the rows of the conns file and draw the points.
   
   for (int row = 0; row < transCount; row++) {
     x1 = connTable.getInt(row, 1);  // column 1
     y1 = connTable.getInt(row, 2);  // column 2
     
     x2 = connTable.getInt(row, 3);  // column 1
     y2 = connTable.getInt(row, 4);  // column 2
     
     //line(x1, y1, x2, y2);
     
     noFill();
     stroke(0,0,0,64);
     strokeWeight(2);
     //alpha(20);
     bezier(x1, y1, x1, y1-30, x2, y2-30, x2, y2);
     
     
     
   }
 }