Design a porch. Ranch-style houses are pretty simple and basic, so it might be best to stick with a simple design. Some ranch-style houses have a simple, unroofed concrete porch, with concrete pillars and some sort of railing and a basic frame extension and roof around the doorway.
Prepare for your new porch. Measure the porch dimensions, clear out any debris or plants in the area and plan how to tie it in to the existing house. If you plan to build a concrete-slab porch, you'll probably have to remove siding where the porch will join the house; that will depend in part on whether your existing house is built on a slab or raised foundation. If you plan a covered entry for your porch, you will have to remove siding around the door.
Build your foundation. If you are pouring a concrete porch, you will have to excavate and prepare the area, then build forms for the concrete; you also will want to install reinforcing bar in the slab. It is best to have concrete delivered from a supplier rather than rent a concrete mixer. If you want to put in pillars at the corners for a railing, install upright reinforcing bar. Then pour the slab. Once the slab has cured, build forms for your pillars and pour them. If you plan a wood railing between pillars, make space for them when you pour the concrete.
Add decorative touches, such as wood railings between pillars or an entryway. You can make a simple entryway by framing out from the existing house a couple of feet, covering it with some compatible siding, and building a simple pitched roof above the door.