To get data for one setup, fill out Setup 1 and leave Setup 2 blank. To compare two setups (currently the "comparison" consists of you seeing both sets of results and comparing in your head), fill out both Setup 1 and Setup 2.
If you dual-wield, fill out both "Delay (Main)" and "Delay (Sub)", otherwise just fill out "Delay (Main)".
"Haste" is optional, but if you have any +Haste% gear, put the effective total here.
"Hit Rate" is also optional. If you want to compare setups that give you different melee hit rates (as shown in a parse), put those observed hit rates here.