As joasis said, ask away. This is a great place to get info and how twos and a lot of us are in the Business.
Any pics of the shed would help if possible.
Is the roof Gable or Hip.
When you said "The whole roof do you mean the framing as well or just the roofing and plywood?
Is there soffitts?
Is there gutters?
What is the overhang in inches?
What is the roofing material?
What roofing material would you like to have on there?
Tear out is fairly simple Gutters, facias, soffitts, gable end siding if any, roofing( A flat shovel works great for this), sheating, framing. Now your ready for the construction and with the answers to my questions above we will be able to take you through this one step at a time, by the way How comfortable are you with roof framing?