Do NOT click away or close this window until you see the success message!
Create a new folder, name it something descriptive.
Copy all the files you need to send us into that folder you just created.
Once all the files are added right click the folder icon.
Hover over "Sent To" (see Figure 1 below).
Then on the fly-out window select "Compressed (zipped) Folder" (see Figure 2 below).
A small progress window should then pop up.
Once finished you'll find a new folder-like icon (looks like a folder icon with a zipper) inside the same folder as your origional folder and with the same name.
Attach that new folder with the zipper to the upload form and when you get a success message you can delete the zip file and folder you created but only if you copied the files into it. Don't delete your files if you need them and you moved them into that folder!