I think it would help to ask those people which things they specifically have trouble with or would like further explanation about, as learning to use a computer is a fairly broad topic.
Provided they understand how to search on google, or open an internet page, you could refer them to a learning resource:
https://www.careertoolbelt.com/5-free-and-easy-ways-to-improve-your-computer-skills/
Or, if you have converse with them, find our where they live (if they're comfortable disclosing their city), and advise them to check out their local library, which sometimes have training to better their skills (especially the physical skills associated with using the computer, like double clicking, typing, scrolling, etc.). Or they could visit a local computer store (like Apple) to get a better familiarity with the device the they're using.
Unfortunately (or fortunately!), as with most skills, practice makes perfect.
edit:
Another thing, make sure to advise those learning to "take deep breaths", don't rush, just take your time to read what you see on the screen. Read each part carefully and make deliberate clicks. You would not believe the number of misunderstanding that happen simply because people rush and click all over instead of read carefully and observe.
