try ...
@echo off
echo Done!!!
sleep 5
What you were trying to do had little point and would have chewed CPU cycles for no reason.
And, the statement ...
set tsec=%timed% + "5"
should have read ...
set /a tsec=%timed% + 5
Can only suggest that you read up more on the set command (set /?) and on some basic programming constructs.
Hope that helps.