There is a lot of conflicting information about how to exactly grow various crops in your backyard. I've had the privelege of talking to various professional and semiprofessional gardeners in my life so far, and The Farmer's Almanac is the only place they consistently point to besides experience on good advice. They will give you planting calendars based on your ZIP code, offer tips on how to care for your plants as well. There's really nothing I can say here that hasn't already been covered in an Almanac article already. I'm just going to stick with pointing out my failures so that you, the paying viewer, do not have to repeat my mistakes.
There's no reason gardening needs to be expensive. One of the main ways I see people get fleeced is by TSC or some other place selling 5x5 planter boxes for $80 a pop, which is ridiculous. What you need to do is find some spare pallets, or old fence pickets (BTW, if you have a source for this you will be set for many other fun projects in your life). I had a tree fall on a couple section of regular 6' fence pickets a couple of years ago, and I just sawed the ends, and butted 2 together with one inbetween for strengthening, and drilled each end into 2 12"sections of 2x4 on each corner. Viola! I'll see if I can get some pictures up here soon.