When you are creating custom code, it is required to be able to see the IDs, Classes and Names of elements that you want to apply style to. 

Internet Explorer and Google Chrome have a Developer functionality tool. Press F12 on your keyboard to see this. 

There is also an option to inspect the individual elements by Right Clicking on the chosen element -> Inspect/Inspect Element. The Developer Tools Inspector will open itself automatically, and the inspected element will be selected within its HTML context. The styles for the selected element will be shown in the right panel (under the Rules/Styles tab), so you can track all CSS changes there.

How to inspect elements in Google Chrome and Mozilla Firefox:

Example of the Developer Tools in Google Chrome:

Example of the Developer Tools Inspector in Mozilla Firefox:

Another helpful tool is a Color Picker. This allows you to get the correct color RGB code in order to define a color. http://www.colorpicker.com/