Hi Rescueandheal,
Building your own screened patio is not a major problem and is an excellent DYI task. Finding plans on line is difficult but I did find a set of plans that you may be able to modify to fit your needs. The link is below.
http://how-to-plans.com/screened_porch_with_shed_roof_plans.htmlThough you could make your own plans and likely do equally well with them. Basically though to do this and get assistance with it you need to provide some measurements and additional information.
How high is the wall from the patio to your eaves (soffit overhang of the roof)?
How high to you wish the roof to be at front of the patio furthest from the house?
How high is the interior floor above the bed of the patio?
How high is it from the patio to the top of the door frame?
Are there any windows that may interfere with covered patio you wish to create?
Do you wish to make the roof larger than the size of the patio so it offers more protection on the sides and front? If so by how much?
I also found a link to a site which offers excellent advice to someone thinking of doing something similar to you. You may find it interesting reading. The link is below.
http://www.askthebuilder.com/B412_Building_a_Screen_Por...void_Headaches.shtmlGood Luck!