My name's Kel.
Will you be doing the work yourself?
How old is your home?
What kind of roof does it have?
Is it properly ventilated?
What style of shingles are you planning to install?
How many separate layers of shingles are there now?
there is 3 but we are removing all of them my house was built in 1978 andyes we are doing our selfs
Check with your local building inspections department to see if your area is considered a high wind zone. Most shingles are approximately 36" wide and 12" high. There must be four nails per shingle for a standard install and six in a high wind zone.
On the bundles of shingles there are excellent instructions for the whole process. It's critical to follow or the warranty will be void.
There are a lot of YouTube videos available showing you how to tear off a roof and how to install.
What other questions do you have?