If you'd like to start this tradition at your house, the first thing you need is a good pitcher. Clear glass is good, because sangria is pretty, but any large pitcher will do. Here's an example from Crate & Barrel. Next, you need a recipe. I'll include links to a few, but to be honest, my version is simple and very tasty.
Here are the basics: a bottle of cheap red wine, sugar, lemon-lime soda, and fruit (oranges and strawberries are our favorites, but throw in whatever you have - lemons, apples, etc). Mix the wine and sugar (to taste - maybe 1/4 cup, but I never measure) and fruit, and let it marinate overnight or until you're ready to drink. Add the soda (again, to taste) and ice before serving.
If you want to go white, get some dry white wine, and then just change up the fruit. Peaches are excellent in white sangria. Kiwis, apples, blackberries.
It's that easy! You can fancy it up however you want. Add a little extra booze for a kick - rum, brandy, gin, schnapps.
Enjoy those Sangria Saturdays!