How to make Blynk rotate a servo

Only if you can provide more information. So far all you have said is “I did what I was told and nothing happened”.
So unless you show us exactly what you have done we can’t help.

For a start a good clear photograph or two showing your wiring would help. What also would help is if you tried to run a simple servo example and not bother with anything else, so that you know your servo works.