in "inc" you put the amount of weight you want to increase each workout, lets say 3,4,5 lbs/kilos/whatever
and in 6th cell you put your RM-max.
Example
Exercise -- inc -- 1 -- 2 -- 3 -- 4 -- 5 -- 6
Squat ------ 5 ---- ----- ---- ---- ----- --100
Then press calculate