Arena questions (Spoilers?!?!?!?!)

Hey guys! I just reached the Arena site (After defeating the *** Artorias, in just 55 tryes) I tryed to have some matches, but i failed. Now, i'm level 47, maybe i'm too low? i just sit there forever, without finding any opponets. Also, how can I invite a mate to a arena match? (I saw somewhere "PVP partyes", i'm pretty damn sure)
Thanks to everyone, see ya on the battlefield

Most players will probably be above level 50. As far as we know the level ranges in the arena are 0-50 50-100 etc. So you'll only play with other players who are also below 50.
http://darksoulswiki.wikispaces.com/Battle+of+Stoicism

I would stay away from the lower soul level arena PvP anyways. Last time I checked the leaderboard I think the top couple people all had modded stats.