$WBINDOF is available for use with all WBSP commands:
texttobesearched - text being searched
texttosearchfor - text sought
start - optional numeric parameter specifying the position inside texttobesearched to begin search. If it does not exist, search begins at the beginning of the texttobesearched.
Number specifying position of first occurrence of texttosearchfor inside texttobesearched after start.
After running this example, the resulting page in browser, may look like this: