While working with WordPress, one would sometimes like to modify the colors of a theme. In order to do that you have to make changes to the CSS file. The main stylesheet used in most themes is called style.css. Here are the steps on how to modify the file-
1. On the WordPress admin panel, goto Appearances.
2. Then goto Themes.
3. Select the theme which you are currently using.
4. Then click on Editor.
5. On the panel on the right would be a list of files currently available.
6. Look for style.CSS
Now you would be in a position to edit that file.