At 13 and being a beginner you may have a time getting buyers. Maybe start with pot holders, candle mats, mug rugs and table runners. They will cast you much less than a quilt and you can sell these smaller items a lot quicker than a full quilt. A good place to sell would be at craft fairs. Maybe start now and build a stash to sell. People like to have the variety to choose from.
Good luck with this. It sounds like you have great aspirations.