Odds are, if you've been interested in running homebrew code on the Nintendo DS, you were probably more than a little lost/confused initially (if you ever got it figured out). There *is* an active community out there, but most of the information is spread out across different bulletin boards, in different threads, often containing more than a little incorrect and/or outdated information, and using terminology/abbreviations you're probably not yet familiar with. Maybe I'm just the kind of person that really likes to have a good grasp of what I'm doing and what all my options are rather than running with "just do X" as posted by some_random_guy023.
Far and away the best write up I've come across is the Running Homebrew wiki entry at DSLinux. It does a nice job of presenting the various requirements and what your options are, the between them such as in which circumstances you can use them and what the pros/cons are, as well as providing links (via Pocketheaven) to specific products/manufacturers.
Check it out and save yourself a lot of headache/irritation.