What year is your bike? You should be able to work it out with a careful comparison of the bike to the brackets shape. Have a look at Ventura's site, they have pictures of most models fitted.
Looking at the part number I'm guessing an older model bike? If you have underseat exhausts I'd strongly suggest bracing it well because a Ventura rack broke my subframe. Fortunately Ventura came to the party and paid up.
I'm guessing you got 2nd hand if you have no fitting instructions so make sure the bolts etc you use are suitable. Most racks come with longer fittings so the new bolt still has the same depth as the original if you follow. Use loctite and be prepared to remove some panels etc while you fit it.
Just have a go, its an easy install on most bikes.