First, let me say that you are doing great. Taking the first step to want to improve your credit instead of deny it is one of the most difficult steps.
Theresa is correct. The first step that will improve your credit the most will be paying off the debts you currently have. As they disappear, your credit score will rise. Getting a credit card, even if secured, will not help your credit at the moment.
You should read <A HREF="http://www.savingadvice.com/forums/showthread.php?t=27">this article</A> if you hadn't already. It will give you a better idea how credit reports work.
Do you have any idea where your money is currently going? If not, sit down and just write your known expenses to start: rent, phone, utilities and anything else you pay on a regular basis. Once everyone knows those, we can start working on the other areas where you are spending. A budget is just knowing where your money is being spent.
Also, what are your current debts that need to be paid off and how much for each one? If we know that people can make suggestions on the best ones to pay off first.
Again, you should congratulate yourself for taking the first step. I know everyone here will help out in any way they can.