Use old Scaffold boards. Draw out your pattern on a piece of paper. Reproduce the shape on the timber, making one step at a time. Each step will be 2 x uprights and 1 x step fixed on top of uprights with screws. Make other steps graduating up to suit purpose. Using fixing straps on the inside, attach one step to the next with screws. Finish by closing the back of the steps by applying timber across the back using screws. Fix to one side a post of wood as an aid using screws. Hope that's of some help.......
Thank you John. I appreciate your time and input.
here ideo how to make one https://www.youtube.com/watch?v=P6yRaTaNsT8