well getting the last row is easy... range("A65535").end(xlup).row will give
you the last used row... so you just have to assign that + 1 to get the next
empty row.. for ex.

irow = range("A65535").end(xlup).row +1

then the data would be put at ... range("A" & irow).value = data....

hope this helps... if you need more help  i'd need to see what code you use now
to get the data from the form  to the spreadsheet