I would suggest you start with some reading....
http://www.wetwebmedia.com">www.wetwebmedia.com</a> is a great site to start with. You might want to order a few books, like the new version of [IMG]http://www.amazon.com/Conscientious-Marine-Aquarist-Commonsense-Successful/dp/1890087998/ref=pd_bbs_sr_1?ie=UTF8&s=books&qid=1214090772&sr=8-1">The Conscientious Marine Aquarist</a>. You can find the old version [IMG]http://www.amazon.com/Conscientious-Marine-Aquarist-Commonsense-Successful/dp/1890087025/ref=pd_bbs_sr_2?ie=UTF8&s=home-garden&qid=1214090772&sr=8-2">here</a> for a bit cheaper but the new version is, of course, a bit more up to date.
Always, feel free to ask any questions here. We try to be gentle with new people! ;)
If I could give two pieces of advice, they would be: 1) Take things slow! It takes a long time to get a pretty looking tank and believe me, it will look ugly before it ever looks pretty. Only bad things happen fast in this hobby! 2) Do not believe anything that is told to you at most local fish stores. Remember, they are there to make a sale, even if it is not the best thing for you or what you need. If you want a fish, have them hold it for you while you come home and research it. If they say, "You need X product", do the research for yourself. There is no one way to do a tank and you will find different advice but some of the people selling fish are no experts at all!!!
Oh ya, and most people burn out in this hobby because they start fast and hot and drop a whole bunch of money into a tank that never works right. Again, take it slow and steady and we look forward to seeing a great system from you. It is not "harder" then freshwater, just different.