i am not quite sure what your refer means?
guess u want get the first blank row,u can use the array formula like this
=MATCH(TRUE,ISBLANK(A$1:A$18),0) then hit CSE(ctrl+shift+enter)
while get the address,u can use
=ADDRESS(MATCH(TRUE,ISBLANK(A$1:A$18),0),A:A) then hit CSE
Hope this can be helpful
Regards,
Sebation.G UK