It's hard to give advice for this over the computer but it sounds like your bobbins aren't wound right. If the bobbin isn't wound tight it can get all caught up. The bobbin should look smooth without any bumps or loose parts sticking out. Also, if you don't thread the needle correctly it will tangle up. It has to be thread though all the loops and holes correctly. Other than that I would say go take a class, it might just be something small! I hope you get it worked out because it is fun to sew for your little ones!!
