peat moss isn't something you need to use.

You're fine still for planting corn, though corn is not an easy crop for beginners, or people with virgin soil.

It is a challenge to turn grass into garden. That soil is covered with turf and has been compacted for years probably. I would not recommend it, it is easier to build a raised bed over the grass.

http://www.backyardgardening.net/art...ised-wood-bed/

If you are insistent on just tilling up the grass, rent some equipment and prepare to put some work in. You need to remove the grass entirely, add in some new soil, and till it all up to loosen it.

Corn, specifically, is wind pollinated so it doesn't do well in small gardens, for best production you need at least 4 rows of it (a bigger area than your average raised bed for sure). On the other hand, with a really small garden, you can hand pollinate it by removing some of the flowers from the top and brushing them on the silks coming out of the top of the ears. But like an 8 foot by 8 foot patch would be more or less the minimum for corn. It also is a heavy feeder (fertilizer, water) and does need loose soil.

I personally try to avoid sod busting whenever possible.

As for the sun issue, "at least 6 hours" is a minimum amount. The ideal spot will get sun from dawn to dusk. Any shade will reduce production. Vegetables really need as much sun as you can provide.