It's not as easy as it appears. I usually recommend a pro does this because we pros can get better finishes than what is available at the big box stores and if it goes bad, you can get them back to fix it. If you do it yourself, you will void any warranty by the guy that did the work originally. Suppose for a minute that the finish he put on fails to adhere well down the road (starts to peel) He could say that is was what you did or the products you used and you be hard-pressed to prove him wrong. But if you're bound to do it yourself, read this:
http://www.hardwoodinstaller.com/hardwo ... screen.htm