Bricks, Masonry, Asphalt and Concrete - How do I pour a 3 foot concrete ramp?

My wife is wheelchair bound. I need to make a permanent concrete ramp for a rise of 7". I would like to just pour a concrete ramp. How do I build the form for this?? I am not a builder but I am handy and if I had some instruction I know I could do this. I need to build 1 in garage and 1 off of back door (same height)
Please help.

I recommend removing the existing concrete in the area of the ramp and replacing it with a solid piece. This will avoid a feather edge at the bottom that will crack and spall off. After the trench is cut out (you can rent a saw with a carbide blade for that), form the sides with plywood cut to shape. Brace the plywood to support the wet concrete and place a stiff mix that has a low slump and can hold the ramp shape. Since it will be a small concrete pour, the concrete expense will not be an issue. Make sure you apply a broom finish to keep the ramp from getting slippery in the rain.