Help with saltwater please

We (and by we I mean people with much more experience than me /site/DesktopModules/NTForums/themes/_default/emoticons/wink.gif src="/site/DesktopModules/NTForums/themes/_default/emoticons/wink.gif" align=absMiddle border=0>) would be happy to help!
A couple preliminary questions. Is the tank you're planning on using new or has it been used for FW? if it has been used for FW was the tank ever treated with any copper based medications?? Copper is poison for many things in a reef tank (other than fish) and so I would suggest either buying a new tank or taking great lengths to ensure there's no copper left (bleaching?)
What type of water will you be using? Water quality is an important component to keeping a successful reef. Many hobbyists invest in a RO/DI water purification system to ensure they have very clean water.
A sump is a great idea, for a variety of reasons, and I'm assuming one of the things that's confusing you on the diagrams you've reviewed is how the water gets back and forth from the display to the sump. First you've got to get the water to the sump from the display which is done either by drilling the tank (on the back panel or bottom panel as long as those panes aren't tempered) or using an overflow box. Overflow boxes have come a long way and have much better designs that protect them from losing siphon, but I personally am not willing to risk it and my tank is drilled. If you're interested in drilling your tank we're having a get together on May 2nd to do various DIY projects and there should be equipment there to drill the tank.
Then you've got to get the water back to the display from the sump and this is where sump construction enters the picture. Most people take another standard tank smaller than the display (20% to 50% of the display's volume is pretty common) and put baffles in the tank to create some sections and also to reduce the amount of micro bubbles that make it through the sump to the display (microbubbles caused by the overflow from the display tank and/or the skimmer) The baffles also allow you to create compartments for optional things like a refugium, skimmer (i would argue this is not optional) and other equipment you might have like heaters, monitors, etc.
My best suggestion would be to READ as much as possible. I read about various setups, styles and theories for about 2 years from the day I decided I wanted a SW tank to the day that I actually had water in my tank. Most people from this club don't prefer posting  to this site too much anymore due to some overzealous mods, but www.reefcentral.com has an amazing amount of information, and a couple great threads in the newbie section that walk you through setting up a new tank.
After you've got the above figured out then we can start discussing lighting, flow and livestock.
Welcome! Where are you located? Presumably the Des Moines area since you found this section of the site?

 

Be more than happy to help, and to assist in building a sump/skimmer.

 

Ditto, if you bring it  they will come..

 

Are you sure you just want a fish only tank? All of the corals and invertebrates are what make it fun... (we will convert you, it just might take a little time and money /site/DesktopModules/NTForums/themes/_default/emoticons/wink.gif )

For a fish only tank it isn't a whole lot different than freshwater. The only difference is that you need salt and a hydrometer to measure the salt... and a protein skimmer is definitely recommended. Another thing is that we don't use airstones... we just add powerheads to circulate the water. (did I mention the fish are 5 times the price and don't come with warranties?)

I've really never had just a fish only tank, but I'm sure you could get away with using treated tap water as opposed to using reverse osmosis / deionized water which is a must for a reef tank.

 

Ive got a 20g that you can have 4 a sump. Beware of the 55g reef tank!