Showing a way to have a level greenhouse on unlevel ground. We made raised beds which match the unlevel ground on the bottom, but are level on the top. We used a metal pole & 'tent' style greenhouse, but it should work for a wood frame and windows style greenhouse as well.
The metal frame pipes are well secured to the raised bed posts.
Propping the greenhouse up on raised beds can be a good idea, even if you have level ground.