We have both in-ground and raised beds. The raised beds are easier to weed, and when planted with the right crops, do well. Don't try anything big like okra or corn--stay with the smaller vegetables like lettuces, radishes, green beans, and bush squash (there are vine types that will overrun your raised bed.)
My only concern is that this raised bed is on your deck. How impervious to water is your deck? You may rot out part of your deck under the bed, but it would take a couple of years or more.
If you are totally new with no previous experience, how do you know there is no place in your yard for an in-ground garden?
How about telling us where in the US you are, your growing zone and perhaps a photo or two of your yard. You'd be surprised how inventive and informative the members are here!