Welcome. One really good way to ease into backpacking is to take your 8-year-old. You mention that you backyard camp with him (her?), so you've already got a great way to test out gear and get your child hooked, too. Others can tell you how to get patterns to make gear - again, let the 8YO help. (They've gotta learn to use scissors sometime - what better way than tinsnips and an alcohol stove!?
) But, seriously, if the child can make up the first aid kits, or pick out the eating utensils at Walmart, or even empty the soda bottles to use as water bottles, they suddenly are invested in the activity.
Your child can probably hike a few miles - which may be all the more you want to try the first few times out, so definitely take him/her.
For summer, it doesn't sound like you'll need a lot of sleeping bag - consider picking up some of those ready-to-sew fleece blanket kits at the Joann Fabric, and make a couple bags (or just wrap up in the blankets, if it's above 70 at night.)
Anyway, you can do this on the cheap - the durability factor may (or may not) limit the length of trip or even the seasons you'll want to take, but it will get you started. If it works, great; you can then move up the gear ladder as you can. If it doesn't stick, well, you're not really out very much.
Enjoy - and take the kid!!