There is plenty of online information. Just Google
"sail rig tuning" and you'll get loads of results from sail and rigging
companies. I just scanned this one
and it meshes up with in general
what I know from working with riggers and tuning race
Your first step is to get the mast in column. Rake and pre-bend, if any for your boat, are boat specific and you should look for information on those from other Simpson owners. If you've not changed the rigging then start with the old settings, which will probably give you ballpark rake and pre-bend and focus on getting the mast in column.
Once you have that set, tighten your shrouds down until they are "snug" and free of any play. How loose your leeward shrouds are when you're sailing is going to be a function of how stiff your boat is. Ideally you don't want them flopping around, but you don't want to over tighten them either, which is a risk on a small cat. Again, if there is Simpson-specific information out there it would be a good idea to hunt it down.