Just be sure to read all our info journals very carefully and you should be fine. :> There's a lot of stuff to read, but it's really worth it and pretty easy to learn, especially after you join and get to do everything.
Oh also, unless your Ice fusion Mareep was hatched in a breeding group similar to ours, you are not able to transfer her in, I'm sorry. :'0 All new PKMNation members get three starter eggs and the Pokemon you get from those eggs will be more or less random, and they'll be your starters. After that you can start buying Pokemon from other members and breeding your own. o/ And if your Ice Mareep was indeed hatched in a group like ours (for example PKMN-Adventures, PKMN-CrescentCavern, etc) you are able to transfer her in, too! If not, you could always breed for an Ice Mareep in the group to be able to use your design, too!