|Obviously you first have to highlight the picture files. For this you use the left click.|
One click highlights just one file.
Left click then Ctrl+A will highlight All Files.
Left click then Shift key will highlight the end of a potential block. Doing this on another file will highlight all files between the end points.
Left click and Ctrl key will add or subtract files from a selection (depending on whether they were already highlighted or not).
Once the ones you are interested in are highlighted you use right click on any one of them to delete (or whatever). There are keys for this too:
Ctrl+C = Copy,
Ctrl+V = Paste,
Ctrl+X = Delete.
This is straight off the top of my head so if you need more info shout back.
Always pop back and let us know the outcome - thanks