Congratulations on your purchase, Technics tables are rock solid and it should serve you well assuming it has been well taken care of. You can find all the manuals for you 'table here: http://www.vinylengine.com/library/technics/sl-5.shtml
The first thing you will want to do is replace the stylus on the cartridge because you have no idea what condition it is in and don't want to damage your records with a worn out stylus. As for the cartridge itself, it won't hurt your records to just try it out so long as the stylus is fresh. However, if you want to replace it, you are somewhat limited on options as your table uses the "p-mount" style cartridges. There are good p-mount cartridges out there, so don't worry about quality, its just that there aren't as many options. Next you'll want to make sure the turntable is level. This isn't as big a deal with linears as with standard turntables, but its a good idea anyway.
Once that's done, plug the RCA cables (red is right, the other one is left) in to the "phono" input on your reciever/amplifier. If you don't have a phono input, you'll need what is known as a "phono stage" or "phono pre-amp." These can cost as little as $35 on up to the price of a family sedan, but they don't have to break the bank to be good. I don't have a separate one so if you need one let the forum know and they'll be happy to make recommendations based on whatever budget you specify. Then connect the ground wire. There should be ground post on the back of the reciever/amplifier/phono stage for this.
Then plug up the power and enjoy the music!
You may end up wanting a carbon fiber record brush to help cut down on static. With these, you want to spend at least $20 because the cheaper ones tend to shed their bristles which kind of defeats the purpose. Stylus brushes are a waste, Mr. Clean Magic Eraser does the job just as well. Just a gentle sweep over the stylus tip between sides and you're good.
I think that's probably enough to get you started. Have fun!
Are we there yet? No, never there yet. Keep it rollin', we're paid by the mile.