I rig the Oasis as follows:
1. The mainsheet runs from the clew of the sail to the microclock that you attach at the aft padeye/handle (not shown here).
2. The sheet then runs forward to another microblock and thru-bolted padeye that you install (see below)
3. Finally the sheet runs aft where you can easily manipulate it and cleat it off (the cleat you install just for this purpose, not related to the rudder cleat; shown above).
Or, to keep it simple, you can just install the microblock at the aft padeye and handle the sheet form there. There are many approaches. The only big "don't" is don't use a swivel microblock at the rear padeye.
This will allow your mainsheet to twist and lock, effectively seizing the sail -- not a desirable result. A simple block is all you want or need.
This may require more line than Hobie provides. I use my own longer mainsheet and a snap hook for quick attachment/ disconnect at the clew. This allows easier sail handling IMO. More stuff on the sailing forum as stringy and reconlon suggest -- tails, boom-bats, mast stiffeners, etc.