I would like to write a program or understand some basics of how it works. I am looking to do something similar to how blogspot (aka Blogger) lets you choose a premade template for your blog and gives you a variety of options for tweaking the colors, background pic etc along a broad spectrum of skill levels.

I don't even know how to begin searching the Internet for articles or anything pertinent to what I am interested in.

Search terms, articles or open source projects welcome.

Thank you.