InStr function
InStr( numbegin, string1, string2 )
Returns the character position of the first occurrence of string2 within string1.
numbegin
Required parameter. Sets the starting point of the search. Must be a valid positive integer no greater than 65,535.
string1
The string being searched.
string2
The string you are looking for.
Example
Sub Main
   B$ = "Good Bye"
   A% = InStr(2, B$, "Bye")
   C% = Instr(3, B$, "Bye")
End Sub