Im trying to write a spell to transform into a raven.

I have the meshes but I don't know how to write the script. can anyone help me.

You might want to have a look at pimpskinny's http://tes.nexusmods.com/downloads/file.php?id=37894, as it deals with shapeshifting pretty extensively. Probably some great examples in there.

You might also take a look at the Curse of Hircine series of mods - they have scripts that transform the player (and NPCs) into werewolves.