The dialogue box here is very similar to the one used for choosing text files; it also allows you to choose from a zip file.

You can use Viewer & Aligner to examine a file: this makes no sense in the case of a word list, key word list, or concordance, but may be useful if you need to examine a related text file, e.g. a readme.txt in the same zip file as your concordance or word lists.

To choose more than one file, hold the Control key down as you click with your mouse, to select as many separate files as you want. Or hold down the Shift key to select a whole range of them.