I have no idea where to start but I do have two helpers thank God
This link should help, Katie:
Make sure you follow ADA guidelines.
always check your area building codes, the ramp needs to be at a certain slope for ada compliance. most are wooden, some have used cement. some areas want side rails on the ramp.
If it's for outside, follow the government safety guidelines and add about 8-10" of width to the ramp recommendations set in these standards. We had one professionally built buy a contractor and the way they built it had two turns off the lane way. They were fine so long as the person goes up themselves, but being pushed the corners are pretty tight. The original ramp was much better thought out and built and cost less than the replacement. My suggestion would be to use deck boards with the rounded edges. That's what was used on the first deck, the second they just used pressure treated 1x6's and the edges splintered like crazy!
Also, check with local foundations, charities, Builder's Associations and the like. Very often they can supply the labor, materials, etc. to help!
In our state, the electric & gas utility company has an Employee Resource Group that partners with businesses and organizations for the handicapped &/or disabled - they build the ramps for free. There are no income guidelines, and they supply materials, labor, etc. It's a win-win situation!
I suggest doing some research or make an inquiry. My son had brain tumors over ten years before passing at age 16. I am eternally grateful to have had that ramp!