where to put thumbnails (and how to name)

I am a truly new users, and experimenting with Exhibit Builder plugin.
I've scanned and uploaded a few pictures as pdf files. Now I realize that Omeka can't natively create thumbnails from the pdf files. I can manually do this - but my questions are:
1. where do I place the thumbnails?
2. what do I name them
3. If I get answers to #1 & 2 will that 'automatically' link the thumbnails to the pages in Exhibit Builder

When you manually create the thumbnails, the easiest thing to do is to add them as files for each item in addition to the PDF. You'll probably want to make the thumbnails the first file for the item.

Then, when you add items to your exhibits, they should just show right up.

OK, thanks for the reply - walk me through this.

I have a pdf named 'test.pdf'.
I created a thumbnail call 'thumb_test.pdf'.
So I upload both files and there are linked -- how?

When you create an item, there is a tab on the left for adding files. From there you can add your files to the item, and Omeka takes care of the rest.