Beginner Gardening: Looking to build a garden or landscape 24x3.5 ft space, 1 by ndkmk

ndkmk wrote:
Hi! I have about a 24 ft by 3 1/2 ft space on the back of my garage. There is currently only landscape rock there, but I'm thinking it would be a good spot for a garden (it is full sun). It is slightly slanted, but not terrible. Pics are attached. A few questions:

- What type of raised garden bed would work best (I'm in MN!)? I've been looking at some cedar ones, but not sure how they'll hold up to our winters!

- Will I be okay planting these on the hill?

- Do I do the whole 24 ft or do something else in the middle/on the sides?

- Any other ideas as to what to do with this space if not a garden?

Thanks!!