BTS Version Upgrade

Hi
I am an Trainee and would like to get information on how to upgrade the BTS.from the omc-r

I need to knw the steps so that i can successfully execute the process

i dont have the version loaded in the BSC or the OMC-R

pls do let knw
1) as if i try this doing deleting the old version and then loading the new version the CELL will go down and it make take time to-up…
2) Suppose if the cell comes up and and some TRM’s have not downloaded the new version what is the steps i should take.
3)how will i confirm my self that the CELL is running on new version

Thanks and Regards
Madhu