Is that possible? (textures)

Is there any way to create a texture from others? I have a tileset, and I want to mix each texture tile (32x32) in a big texture (it will be the world map)…

That’s generally something you do before making it into a texture.

Yes you can.
This is usually done either as an offline process or a pre-rendering process.
Use a framebuffer object and blend or whatever your tiles on to that. Save the FBO texture attachment image as your new texture.
You don’t have to use FBO you could just reuse the standard back buffer if you wish.