You can create a game and write in a description to indicate you are learning how to play. If there are enough people online (usually in the evenings), someone may join and help you out.
In case you're not familiar, here are the steps.
Play now -> Create new table -> Launch table -> modify
Alternatively, if there aren't enough players online, you can create a meeting. A meeting is just a game that is scheduled to occur within the next week or so. You can set the time and description, and any interested people can join the game. I haven't used this feature before, but I guess you just have to remember to come online at the scheduled time (and hope the other player(s) do the same).
I've learned to play many games on this site, although I always read the rules and/or watch a video tutorial beforehand. I find most people are open to helping others learn.