Wood Stairs

You could go to your local hardware store and look in there books on stairs and steps, or look for decks and patio's, they will step you through building safe steps and handrails for your project.

Your local Home Depot or Lowes carries pre-cut stringers for that size drop if you don't want to design/build your own.

Average risers are about 7". 7.5" gets a little steep but 6.5" makes a nice height step and especially for older people. Average tread depths are about 11". 10" is a little short but 12" makes for a nice size step. Basements may have short and steep steps because of the total rise and length you have to deal with. However, for decks and porches a 6.5" rise by 12" tread is nice to walk on.

For yours, a 42" rise divided by a certain number of steps gives you your rise. Either 42/7=6"rise or 42/6=7" rise. Figure in your tread depth and you can calculate the length of board needed. Get a book though cause you need to get the top and bottom steps right or you wasted the board. The bottom step may be shorter and the top depends upon how you tie it in.

Also for 3' wide steps for decks and porches, I like to use three 2by12 stringers. The middle one helps make it more solid and takes out the bounce.

Actual construction could affect how you cut your stringers depending on such things as does your top tread start even with the top or is it actually the first step below the start? Do you have treads where the nose extends over and past the riser? Are you going to have a solid riser or leave it open? Many variables. Good luck.