couple of dice probability questions

i am not sure if this is in the right place, however if it is not, could a mod or admin kindly move it, thankyou.

ok, i am stumped trying to work out the formula for a spreadsheet to work out a couple of things. i have googled but nothing seemed to cover my exact topic

firstly, how would i work out the probability of rolling over a certain number on a six sided die which if not over that number could be re rolled once

secondly, how would i work out the probability of two dice being over a certain number?

thanks in advance!