You cannot edit it online, you must download it as Excel or Open Document Sheet and open on your computer with the appopriate software. At least the conversion from and to Excel and Google Doc worked so far for me.
Here's a screenshot of the relevant part:

At the top, you can first select the "rules" on how heat sinks operate - The values are preset to how things work right now, but you can adapt (let's just hope they are not making things even more complicated!)
In the next table, you can select how many single or double heat sinks you have. (Don't mix them, the sheet isn't prepared to handle that - you'll get unrealistic figures since the heat capacity will likely be added twice)
Then, in the first colored table, you can choose the weapons you wish to equip on a mech. You can also select on the most right column whether the weapon is actually to fire or not - this allows you to test different firing configurations.
And finally, at the bottom, you can see the results - how much DPS your current build theoretically generates, the amount of heat it generates per second, and how much heat it gains after substracting your heat dissipation, and finally, how long you can fire at the listed DPS before your mech will overheat.
Below that, it calculates the damage you can deliver until the shutdown, and to compare the damage you can deliver after 10 or 20 seconds of continuous firing.
This should give you somewhat of a hint on how "hot" your mech runs. My advice would be to try to find a build that doesn't overheat in the 10-20 second range, and then try to to optimize your damage output.
For now, the range listings and the recycle time are unused - I may use them later to give you damage estimates by range. For now, you may want to use them to decide what weapon groupings are to be used.
Not shown on this table is the table for the individual weapons. THis is pretty much the same data you may find in Ohmwrecker's charts. If weapon stats change, you can manually edit things. ANd for the theorycrafters out there, you can also use this to see how theoretical changes would affect a mech loadout.
Edited by MustrumRidcully, 20 November 2012 - 04:09 AM.