I'm attempting to set the inside color of the widgets on my sidebar as white so that the text is visible. Does anyone know the best approach for this. You can check out the Site to see what I mean. The last widget on the bottom of the page is white inside but I don't know if I need to approach this in CSS or PHP.
I went to your site...what specifically are you trying to change the color of? Like what does the content say?
I would suggest using CSS as that is for styling HTML pages. If you are using Firefox, I recommend using the plugin Firebug which allows you to inspect the HTML and CSS. With Chrome, this feature is already built in and you can simply right click on the page and select "inspect element." Once you find the element(and more specifically the class or id of the element), add some CSS. Find someway to override the CSS on whatever platform you built your page on (as in where to place the custom CSS file).
For example, if you wanted to change the whole background of the main page(minus the grey edges), in your CSS file add .container{background: green}.
If you specify what you are trying to change I can help you specifically. And upvote people's answers like the people above said so users will want to answer your questions :)