Not that I know of, but many users here are experienced in the art. I can’t send you screenshots right now, but here is my method:
1) Click “Edit Page”. This will be at the top of the page either in a blue button in the right corner and/or as grey text under the title
2) Ensure you are in Visual Editor, especially when starting off
3) Edit the bits you feel need changing
4) Describe the edit in the box (you’ll need to click “Next” if you are on a phone). I don’t know how useful this is, but I do it anyway
5) Select if it is a minor edit (e.g. correcting grammar/cleaning up the page a little) or not (e.g. adding extra info)
6) Select if you want to follow the page (I believe this means you’re meant to get notifications, but I have never received any)
7) Click “Done”
8) Revel in the fact you just edited a page
Creating a page is a bit more difficult, but I can explain that if you want