This video will show guided steps on how to cut out and replace a rotted section of plywood subfloor beneath a toilet caused by a cracked leaking toilet floor flange, cut out and replace the immediate section of PVC sewage/drain line and replace the toilet flange and flange seal, both with better versions, lay down new vinyl flooring and reinstall the toilet.
In this application the flooring was sheet vinyl which I was replacing with the same as it's a small bathroom and this is a quick and easy way to finish.
If you have a tile floor over plywood subfloor, the rough carpentry and plumbing steps will be the same. However reinstalling or replacing the tile in the immediate area will of course be a much trickier issue and beyond the scope of this video.