battlebox games are usually the best starting point for any new player. For Circle you would be looking at non-epic Kaya, a Warpwolf, and two argus (two headed wolves). You could just start by picking up around 12 points worth of models. This is a little tuff unless you research it online first. The point costs for the current mk II hordes models is post on the privateer website. The important information to note is that in Mk II your warcaster/warlock does not actually cost any points, you just pick your caster and use the points to field your army. Each caster will alot you bonus points, these are listed on their information cards. These bonus points are used to get warbeasts only. So, in reality a 12 point game with kaya who gives you a bonus 6 points for your warbeasts is actually more like an 18 point game.
If you choose to not go with a battle box though, I would suggest you research the models a bit. I have a Circle army and they are fairly easy to play and learn with. Their Forces can vary alot from player to player, some do constructs and some like the big Werewolf armies. Its up to you on what you think looks cooler though in the end