I know this sounds belittling but go to your SDK manager and double-check that everything installed properly. The Google API's have a knack for not actually installing until you explicitly look at them. 

already done tha, still have the same problem. thanks anyway

This has to be one of the most frustrating things involved in developing for Android, along with getting the device drivers and adb to work.
I had this problem, but I can't remember how I fixed it.
You start by... reinstalling the SDK.
If that doesn't fix it, then the problem is more deeply rooted than in the SDK installation.
Other people have also had problems with the SDK, although I'm not sure which ones, if any, will be helpful.
Also, AK Eric has done a lot of stuff with Android and his blog contains useful information.

i reinstalled everything, now i got the same problem but the error seems to be different, this is what i can read:

An error occured while running "android create avd"
The default android emulator could not be set up. make sure that the android SDK is installed properly and that the android and google APIs are installed for level 7,
(Between you and me, occasionally, this error is a red herring, and your sketch may be launching shortly.)


i'm sure that i installed the android SDK properly, i followed every step.
don't know what is to be installed for level 7 and don't understand the last line about the red herring
has anyone had this problem?

Okay.
I think that your SDK is installed properly.
The problem here is likely the name of the emulator, although it could be something else.

What version of processing do you have?
For me, I'm using 1.5.1... The emulator is named Processing-0197.

If the emulator doesn't exist, then create it. Processing might not have initialized it properly...
Start the emulator to see if it works properly.

At this point, if it doesn't work properly, I would have to see the stack trace.

Wait...
Did you do anything?

In the SDK and AVD manager, you can look at your virtual devices...
That's what I meant before, although I'm not sure whether or not you realized that...

been trying to open the sdk and avd manager but i can only find the one named sdk manager, wich doesn't have virtual devices option.
don't know if it helps but i'm a mac user, maybe it has different tools i don't know, really clueless right now

Okay...
It is called the SDK Manager.

On the left, you can look at several different views:
Virtual Devices
Installed Packages
Available Packages
Settings
About

You want to select "Virtual Devices" (AVD stands for Android Virtual Device, if you didn't already know that).
There, you can see a list of all of your virtual devices.

If you don't have this, then...
I've never encountered this problem before. You should try to get the SDK Manager...

that's what i meant before, there's nothing on the left
this is exactly what i have:
http://wiki.processing.org/images/e/e3/Android-sdk-manager-15-macosx.png

That is... odd. I guess Mac has a different way of doing things...

According to the Android Developers Website, the SDK and AVD Manager should look like this.
You will probably get better advice from a Mac user that has done this before.