You can sign up as a worker at https://www.mturk.com/mturk/welcome. It really does not ask for that much information and once you start earning money, you can transfer the money earned into an account with Amazon for shopping. It does take a while for the money to show up in your account when you are new though.
Once you sign up, there are many HITs to choose from. I personally enter $1 in the money amount and check off "show hits for which you are qualified" before searching for HITs. It really helps narrow down the search. There are so many HITs that are only worth a few cents and not worth your time. However, it can be a good idea to do some of the low paying HITs at first so your have a high approval rating and you can get used to using the system.
I have been using Mechanical Turk for about a month. I don't find it to be terribly difficult to use, although it is confusing at first since your account balance takes a while to appear when you are new... about 2 weeks. The money is not that great, but if you don't mind doing some surveys in your free time or writing small articles, it is not difficult to make a couple of dollars in an hour or so. Good luck!