This is a handy page for testing out how various colors go together when putting together a website, when trying to make certain that text colors don't clash with the background and are actually readable.
To use this page, enter in the RGB values as a 2-digit hexadecimal number in each box (each digit being 0-9, A-F in value, for a total base-ten value of 0-15) combining to a total value of a number of 0-255 in each box. Then hit the Apply button to apply the font color changes.
When you find a color combination that you like, run the 3 values together into a single 6-digit number and use them as your RGB color code.
For example, if you use the code <p color="#FF0000">testtext</p> the testtext will be show up as red on the screen once you implement the code.
A website that contains a reasonably easy to use lookup color codes is http://html-color-codes.info/ with links to different ways to view the colors. If you don't like that site, I suggest googling for "HTML Color Codes" to find another site - there are lots out there. Alternatively, you can use the w3schools page which lists the "Web Safe Colors" which is a list of colors just about guaranteed for all computers to be supporting, even older ones. You can find their site at http://www.w3schools.com/html/html_colors.asp. Lastly of the sites that I am linking, there is Wikipedia which can be found at http://en.wikipedia.org/wiki/Web_colors.