How to paint UV textures?

Hello!
I know hot to unwrap UV etc., but i don’t know how to paint it. I don’t know how game makers do it.
( Sorry for my bad english )
I can’t paint, it’s ugly as hell.

When i unwrap and export to GIMP or photoshop, don’t know what polygon what part is etc.

Thank you.

If you want to paint your image inan external editor:
Step 1: In the File / User Preferences / Addons / Import-Exportensure the UV Layout addon is enabled
Step 2: With the UV layout visible in the UV/Image Editor window use UVs / Export UV Layout menu entry.
Step 3: In the file browser window that open select where you want to save the layout and in the bottom left corner set the output format and size.
Step 4: Open in your image editor.

Thank you dear Richard, but i think here is a problem.
1 - When it works, ( sometimes works only, don’t know why, or what i’m doing ) whenever i edit in GIMP,can’t save, because ‘‘An another program has using this already’’ ( Sorry for bad english again ). It’s a lot of time to paint a texture with this method.

2 - When it don’t works. I can export, import image, add new image, replace etc., but the model has only a totally black texture( or white ).

Sorry Richard, i doesn’t understand this. Sorry for disturbing.
Thank you!

You can do Texture Painting in Blender.
Here is one tut:

Thank you Richard and FloridaJo