Well, you're doing it - researching!
What you need to do is a little reading on what kind of tank you want - do you want a reef tank with corals (if the lights you have can support them) or do you want Fish Only With Live Rock (FOWLR)?
Reef tanks are more compicated ands require special lighting and there is less room for error with your water parameters. Do you have any test kits? What kinds of supplies were left with the tank if any? (chemicals, salt, hygrometer/refractometer, etc...)
There are many "stickies" on canreef that yopu can read or you can look on the internet as well, here are some links for beginners on canreef, as well check out the "Reference library"
http://www.canreef.com/vbulletin/forumdisplay.php?f=51