So if F6 < 5, you want your cell to show "1". If F6 > 5, your cell should show the value of "DED!A1:A11,2"? I'm not sure what that means. Are you looking for the SUM of the values in A1:A11? Are you trying to do a VLOOKUP from that other sheet based on the value in F6, and getting that value returned?

If you simply wanted the value from DED!A1, the formula would be:

=IF(F6<5,1,DED!A1)

Another question - what do you want to show when F6=5. The IF statement (above or yours) does not account for that. It could easily be incorporated, though.

EDIT: Looks like Noob beat me. That'll teach me not to refresh my browser.