If you are using Microsoft’s Notepad as your text editor you should get a source code editor to use when viewing and changing CSS, HTML and PHP files. Such an editor will have code syntax hightlighting and other features that make the job of viewing and editing these file types easier.
A simple and free programmer’s editor is Notepad++. If you are not doing much work with CSS, HTML and PHP, this would be my choice.
Wikipedia has an article that has a list of of text editors and a simple comparison.
A web search for text editors and text editors comparison will yield a lot of information.