I feel it’s important for you to understand the structure of a set of stairs before you get out your saw and framing square.
To lay out a set of stair stringers from scratch requires a little math, but not much. Equally important is some quiet time to run the numbers and at the same time to think about the construction ...
My old wood deck is deteriorating and the stairs could be hazardous. What is the easiest way to install new ones for an inexperienced DIY-er?