Don't kick yourself for it not working, either. It is not easy the first time. The first gun I ever sighted in was my 7mm-08, and it was a pain in the ass, to be frank. Took me two attempts, actually. It was hitting fairly well after the first attempt, at 100 yards, but then at 200 it was hitting a foot to the right. Took the whole scope, mount, bases, everything off and started all over again.
If you can get it to hit the target at 100 yards, you've got a route mapped.