How much lumber and supplies will I need to be a 14*40 foot shed

I agree with the contractor idea. If you plan on doing it yourself, you need to go to Lowe's and ask .

There are kits for sheds. You can buy to do yourself or get it done by them . I built my own. But that was years,ago

I could help need to know what budget you working with

You need to get with a contractor to figure in what kind of shed ya want. Example: shingle roof or tin roof. Any windows? Garage door or home door. Ect hope this helps