[amibroker] peak exploration help needed

[mahest72]

i have made simple afl 
Filter =1;
Buy= C>Peak(Close,1,1); 
Sell= C <Trough(Close,1,1); 
AddColumn( Close, "Close" );
AddColumn( V, "Volume", 1);

but i dont know how to addcolumn to list peak and trough.can anyone 
help me out

regards
mahesh