HELP, problems with Serial.readString()

Sorry, I forgot that this "forum" has no reference for String
So I used Mrs Google to look for "String in C++"
And here is a link to "compare" function / method.
Study it and then come back for more help.
It is really not that difficult, after you get out of "cut and paste" mode.
Try it.

http://www.cplusplus.com/reference/string/string/compare/