2
you mean the weight?
you want the main menu to be on top..
then login screen below it?
yes you can by going to system admin -> blocks ->
Look at the column WEIGHT
there u see lots of numbers.
by default its 0
so if you put 1 it would be on the top.
put 2 it would be on the 2nd
put 3 it would be on the 3rd
and so on and on...