Unfortunately, you cant do any aside from sending a message to your phone through your apple id, given that you have your apple id associated to your phone, and assuming the one who stole has wifi connection, you may delete your iphone remotely too, which in this case, your about to give up your phone, unless otherwise the one who stole planning to return it, which is quite impossible, but s/he cant use it anyway, then you are lucky. Just remember to provide you contact info on emergency message