Though this has been placed in the Requests section...

I posted a request about what program is used to make a banner for your sig and how to use it. The user that answered said to go here and ask for advice. Can someone help, please?

Alternatives to photoshop are preferable.

GIMP? It's essentially a free Photoshop. Naturally it has less options (or so I'd believe), and the interface seems a bit less intuitive, but I hear it's pretty good as an alternative to PS. (Haven't used it much myself).

I recommend Paint.NET : http://www.getpaint.net/

It's interface is easier to use compared to GIMP, IMO. It's also free.

Paint.NET Tutorials

any program that's 2d like will work for what ever you maybe doing unless your doing 3d models which is totally another thing which wont concern sigs.