First of all, my suggestion for you is- go with the necessity. The idea behind DIY is to save money, and what is a better way to save money then building something you really need (though I wouldn't start right away with something to complicated). A good website to start with is BobVila. this guy has a TV show of DIY anf the website is sorted by subjects like: bedroom, roofing, decks etc. There are all kind of project which includes specific directions, tips and sometimes video clips of the actual work.