How do I Paint on has an Image that is used as Texture? (I don't have any access to external programs, nor the patience or time to learn them. I want my Blender problems to stay in Blender.)

I have a Picture inside my UV Editor, and I wanted to know a way to apply a material, color, or paint to affect this image, or my mesh.

'This picture wraps around my barrel. I have cracks in the wood itself, and separating the individual planks. I want to apply 'black' to those cracks.'

I wish I could provide visuals, but apparently the 'Blender Forums' doesn't allow 2 images.
To paint on a mesh in Texture Paint Mode you need a UV unwrapped mesh.

Then, there are a couple of options:


Paint on a texture using the UV editor.

Enable Paint Mode and press T to bring up tools for painting

The image below shows where you toggle paint mode on



Choose the tool you want to use, and paint directly on the image.




(Please see this link for more info)


Paint using the 3D viewport.

Enable paint mode, select your tool and paint directly over the mesh. 




IMPORTANT: After you've painted on the texture you need to save the image on the UV/Image Editor. Use Save Image on the menu or AltS to overwrite the original image with the changes or use F3 to save as a different file)



If you don't save the image and close blender, all of your painted texures will disappear forever

You might also find this pages from the blender manual useful:

Texture Painting

UV Unwrapping a Mesh