How to prepare my backyard for gardening for the first time

http://www.theprairiehomestead.com/2014/09/beginning-gardening.html

https://www.bhg.com/gardening/yard/garden-care/building-a-new-garden/

Depends whether your going to grow on the ground or use raised beds? If on the ground, you‘ll want to rototill the ground and personal the first garden I ever did that’s all I did and planted everything and I had a great crop! But you can add other materials if you like? I do raised beds now since my wife has bad knees she can’t bend down to the ground any more. So I buy 4 to 1 garden soil from my landscaper in my area. It’s a little better stuff then what you get in the bags at Home Depot. A lot depends on the soil you already have, is it good soil or clay that water won’t drain thru? If it’s clay you’ll probably need to amend your soil a little and rototill the heck out of it the best you can to get all the lump out! If it’s clay ground, you may want to consider a good raised bed and put a bunch of good garden soil at least 6”-8” High or better! My beds are 16” high, but that’s a lot of cost in extra dirt! So whatever your budget allows you to do? I’ve found more often then not just plow the ground good and plant your seeds and the garden does fine too! How fancy you want to go is up to you!

What do you want to grow? Perennials annuals or vegetables?

https://www.bhg.com/gardening/yard/garden-care/ten-steps-to-beginning-a-garden/