I'm making a simple website for my small business. Luckily, it doesn't need too much functionality, but it does need to look good. Do you know any good websites or books that can help me know how to make my website look appealing to my customers?

Making it look good requires visual/artistic skills, which you either have or not (I do NOT, and I don't know how to get them).
You could probably find some links at:

www.w3schools.com (extremely thorough, all about HTML)

http://www.mcli.dist.maricopa.edu/tut/index (very nice site at Maricopa College)

Mike Huffman has a great site, with lots of computer info, including HTML:
http://www.mhuffman.com/resource/index.html#html

Are you looking for more information on this, or is the above post sufficient?