There are lots of resources on the web for composition.
Wetcanvas has tons of information in their Composition and Design Forum:
- Visual Associations and Communication is a great start on how to communicate within a painting.
- A Composition Checklist is a great list of things to check for.
There are some very good articles on composition as well.
- Composition Color and Contrast
- Landscape Composition Rules
- Composition, Understanding it - Using it!
- Composition in one easy lesson
- The Alexander Painting is my favorite because it not only covers composition information, but a view into why something worked and did not work in a painting and how he came to the end result.
Some other resources for composition that I found useful are:
- Art Composition and Perspective in Paintings
- Art Composition and Definitions
- Composition and Design Principles
- Percy Principles of Art and Composition
Composition is a huge subject. It can be overwhelming. I don't think it is something that can be learned in a few easy steps. I think it is something that you have to jump in and try over and over again.