I have never had a vegetable garden, help?

I would like to have a vegetable and fruit garden. I have 40 feet by 25 feet I can use for the area. Here is the twist, I can't kill any grass, so I have to use above ground pots or something... If I can't kill any grass, then what should I do? Are there any types of things where you can have a serene peaceful garden, yet not kill grass? I have been going through such a hard time in my life, and I feel if I have this garden, then I will be happier because I love nature. I don't know a thing about gardening though, I don't know how to start or anything!!!!!!!!! Please help!!!!!!!