To bake to an image:
First, make sure your model is UV unwrapped.
Next, set up your material the way you want it. (A material is your entire shader setup, nodes, etc. while a texture is just an image that you use somewhere in that setup. Material = shader, texture = image.)
Add an Image Texture node. Don't connect it to anything, and make sure it's selected.
Click the New button to make a new texture. This is where your bake will end up, so make sure it's the size you want.
Head to the render settings. Switch to the Cycles render engine and scroll down to the Bake section.
Choose the Bake Type that you want. (Normal, Diffuse, etc.)
If you're trying to just bake the base color, choose Diffuse and uncheck Direct and Indirect.
Then click Bake! It bakes to the image in the selected image texture node. It may take a minute or two.
Please note that the target image will be totally overwritten, so don't accidentally use an important image.