How do I complete the mission "Eden Prime: Resistance Movement"?
You need to pick up three pieces of intel on Eden Prime to complete this mission, it sounds like you only picked up the first one. You can see this walkthrough on the Mass Effect Wikia for the locations of the intel.
I suspect that reloading a save where you're still on Eden Prime or haven't started the mission yet is your only chance to complete it, if you can't visit Eden Prime after finishing the main mission.