How can I get some cinderblocks to lay perfectly flat and level in the dirt?

I don't know if is the right place to ask but over the last couple of days ive been trying to do this and im about to start ripping my hair out over it. Its 4 blocks in 2 rows. Best way I can visualise that is like this == imagine each line is a block and are touching. Im putting 2 flat square pieces on top and cant have it wobble at all. I'm using a square shovel, a level, and a long 2x4.