background help

I am very new to after effects (two day user) I am however very versed in photoshop. What I did was a record a video with a sheet as the background in green however its the wrong shade of green (army green). I would like to remove the bckground and place our company logo behind it. This is what I want it to look like but the rotobrush tool is very annoying. Is there a way to easily isolate that background color and delete or if any of your pros have a better way to help that would be great. Please don't just paste a link to another thread. I have done my share of searching (6 hours) and could not find a great answer.  Thanks Brad