french patio door replacement
Just a guess here since your post is a bit vague, but I'd say you have a standard 60" x 80" patio door. A french door would have both sides able to open, there are a great many styles of doors that you can purchase to fit the opening you appear to have. This isn't a job you'll be able ot handle on your own without some assistance and if you've never set a door before, I wouldn't suggest you try this as your first.
All you need is ignorance and confidence and success is assured. - Mark Twain