How do I get up on High Hrothgar to the Greybeards?
Solution 1:
There should be stairs near a bridge in Ivarstead (you know you're near it when you can get a quest from an npc to deliver food to the Greybeards), just go up those, however sometimes they end for a bit, however the path is generally linear to High Hrothgar. Just look around for some more steps.
The UESP page for the quest is a bit vague, but might be of some help.