It depends what you want the pattern to match. As a regex,
   hello*goodbye
will match any string that contains "hell" followed by "goodbye", with any
number of "o"s between them, e.g.
   hellgoodbye
   hellogoodbye
   helloooooooooooooooooooooooogoodbye
.
If you want to match any string that begins with "hello" and ends with
"goodbye", use
   ^hello.*goodbye$

And read the documentation!