You're about to get a crash course in CSS by learning how to do a mouseover like this:
Making External Style Sheet
Making An External Style Sheet
First thing we are going to do is make a CSS file, better known as an external style sheet. Oh relax it's going to be easy. The external style sheet contains nothing but CSS code. From this one file it's possible to make changes to all your webpages at once.
To make the external style sheet open any text editor such as Notepad. and save the blank file by choosing Save As, give your file a name, any name you like, for example mystyle and add the .css extension to it like so:
You've just made what's called an "external style sheet", aka CSS file. Save the file in the same folder you keep your webpages.
Next open up a webpage and put the following code between the opening and closing head tags:
Every webpage containing that bit of code will display things according to what's in the external style sheet named "mystyle.css". Replace mystyle.css with the name you gave your CSS file and you're all set to write your first piece of CSS code. So let's make our Mouseover.