I filmed our entry onto a car ferry, which was very dark. Messing around I found a way of lightening the captured clip. When it was done a brush & dustpan appeared below the clip. I now have other clips I wish to adjust, but I can't find out how I did it. I have tried putting the instalation disc in again to look for a tutorial but that did not appear.Can any one tell me how to do this

There are several free plug-ins that can do this job, e.g. the plug-ins of Werner Loettgen (WL filter).
Look HERE for installation instructions