[amibroker] Backtest sell for a timed sell

[snappyk1]

I am new to this and the answer should be easy, but I don't know where
to start.  For a sell rule in a backtest what is the code for sell 7
days after a buy?   

My idea:  what would happen if you buy when the 2 day average crosses
above the 5 day average and sell seven days later?

Thanks for any help.