All I want to know, is how to select multiple photos in an album

Hi - 3 ways:

1 - Drag a selection box over them (starting on a gap between thumbnails)

2 - Hold down the CMD key while clicking on individual images (for a set of pictures not next to each other)

3 - Click the first one you want to select, then Shift-click the last one - to select a range of images.

2 and 3 can be combined - so you can then select one range, then with the CMD key pressed select more individual images, or select a second range.