You most likely won't be able to start your own brand from scratch with only a few bucks. As someone who wants to be a designer I can tell you that's just not how the clothing industry works. However if you really were serious about doing it from scratch, you would need experience. Do you know how to sew at least?

Your best bet right now would be to use something like RedBubble or Threadless. Now I honestly hate those websites because they take such a big cut of your profit, but it's better then nothing. Especially considering you don't need to pay to leave your product up, handle shipping, or the printing of your products. It's a steady income if you make something successful after you've finished making it.