Find the save file you want to edit and double click on it to load it into the program. EMS is Galactic Readiness percentage x Total Military Strength (achieved through War Assets). However, it is not the deciding factor on whether you get the Perfect Ending with the clip showing Commander Shepard waking up. It can only be increased by playing multiplayer. To clear up confusion regarding Galactic Readiness: Clear up the Confusion! Galactic Readiness or EMS? Playing multiplayer and building up your Galactic Readiness can double the effect of your Total Military Strength, but you can also achieve enough War Assets on your own tp make multiplayer unnecessary. The Galactic Readiness percentage can only be increased by playing multiplayer.

So, if you have 5000 Total Military Strength and 50% Galactic Readiness, you have 2500 (5000 x 0.5) Effective Military Strength. EMS = Total Military Strength x Galactic Readiness percentage.