what size tank are you using?
this will depend on how mig your sump needs to be. a good way to build a sump is to build it as big as possible can fit under your aqaurium (if this is where u are planning to put it).
follow that GARF instructions on building a tank, then ad the dividers etc as needed. i have a 90 gallon and will soon be running a red sea berlin turbo in sump. some skimmers work along side of the sump or wet dry others work inside the sump. this will also depend on how big ur sump needs to be.
as for what you'll need to build your sump, one of the more popular ways to build one is using acrilic. some people use rubbermaid tubs, and this is a cheap and easy way to do it if you short for cash. if you're using acrillic, you'll need to get a plastic supplier, some acrillic cement and a good set of plans.
im in the process of building a sump for my 90 gal
so if u have any questions u can ask