If you've the gumption to install your mast you can tune it. No problem. Riggers are mostly used on large boats with complex rigs. Your boat is definately in the DIY category. Anyway you've gotta learn how anyway as you'll be undoing a stay here and thier for ne reason or annother. You could have a rigger teach you as they go.
So how do you know what to do. There's books on the subject. Brian Toss' book "The Rigger's Apprentince" is the most encyclopedicthat I know of. It'd be best to check it out of a library as you'll only be using a half dozen of its 392 pages at the most. Still it's a good reference. Toss also sells a DVD on how to tune your rigging on his website. If you're in the Seattle area he also runs classes from time to time. Check out his website.
Riggers can do the tension by feel, as do most all of us. But the really sane thing to do is spend about $80 to get a rigging tension gage. Better still borrow one.
Contact the class organization for your boat. They usually have all the tribal knowledge on thingson how to best set up your rigging. There may be someone in the area who'd be glad to help.