I just bought an HDR-SR11. I'm new to videocams and I want to edit my footage. I'm testing Sony Vegas trial to see if that's the software that would be helpful, but so far I have not been able to open any file that I shot with the Sony HDR-SR11.
Any suggestion what I need to do? install? or disable?
Any help is much appreciated

Not enough info.

I think you need to grab the last update of Vegas to get AVCHD support. I think the trial version isn't the latest version. There are plenty of Vegas users on this forum, so I'm sure somebody will be able to confirm that.