I searched around for some answer and came up with a few posts but could understand if buying the Custom CSS pack was enough. I read somewhere on the site that CSS package doesnt allow blog width to be changed.
How can I change the blog width?
Also it doesnt say what kind of customization i can do with the CSS pack… can I essentially design my own theme with my own background images and stuff or can I only alter current themes?
You can change blog width and the width of the sidebar, or whatever. What you cannot do is add funtionality such as adding top navigation to a theme that does not have it and things like that. Many people here change the width of themes with the paid CSS upgrade. If you have not seen these, you should read through them: