dont apologize for noob ?? thats the point of the forum( well one of the points)
A sump is basically a the area in wet dry filter that contains for lack of a better term extra water. In it you may have a skimmer, live rock, its almost endless the configurations you can come up with.
If I could suggest if your in no rush spend some time looking into the different filtration and tank design before you just but a tank and filter. There are a lot of good sights that are not forums you can check out, buy a book or 2 I only say that because this is one of those hobbies that if you dont reasearch before you purchase you really can end up spending way more in the long run.
Hopefully that didnt scare you away cause it is really worth the time and money as a hobby.
Now to answer your question on skimmers
4 units in hang on that i could tell you to look at
1 Auqa C remora, i know some people on here use it and are happy, its retail in the $150 range i think
2 Red sea Prizm similar cost ive used it, pulls lots of skimate but needs constant adjusting
3 Bak Pak 2R same cost and dont really know much about it
4 Sea CLone 100 cost around $100 alot of people hate them, I have one on a 75 and it take patience but works well for me( neede to add a sponge as a bubble trap DYI project.
The other option is find a used one someties you can find very good units a great cost, look on the usaully auction and classified sites.