Architectural drafting for residential home

We have a terrace house with a single floor addition at the back of the house. The roof of the addition sits just outside our existing kitchen on the floor above. Currently, the kitchen has a pair of French doors opening on to a small balcony that sits adjacent / just along the front edge of the addition. We would like to extend (replace) the balcony with a large deck that sits over the entire roof of the addition. The deck needs have a privacy screen of some sort - we are thinking of placing large planter boxes along the edges of the deck, so the deck would need to be stucturally strong enough to support growing shrubs / trees. At the moment the small addition has small eves, so we would like to extend the eves (or create large eves with the proposed deck) so we can store our bicycles away from the weather. The size of the deck is approximately 20 sqm and we can provide current plans as a basis to design the deck upon. We require the design to be presented in: 1) CAD drawing(s) with vertical and horizontal presentation; 2) Sketchup or similar CAD program to help visualise the design; and 3) suggestions to improve the design.