i just bought 2 used 7290's off of ebay and when i put my sim card in the wrong number shows up under "my number" regardless of the phone i put the card in. how do i change this and is it going to cause a problem in the meantime? thanks guys for any help, this is my first blackberry so i may be on here a lot asking questions

You number is on the sim card. If you go to Options>Advanced>SIM Card - You will see Phone Number and you can edit it there.

I can't edit my sim number over there...it says SIM Eror.