This may sound really stupid, but how in the heck does the windshield wiper arm connect to the post? I ordered a new one and rec'd it a new blade in the mail today. I am at work and away from the truck but all I see is a spring where it would appear to connect. I am sure I am going off the deep end even asking this but any tips would be great appreciated. Now, where are my meds?

I probably should have also mentioned, I have the stock vacuum assembly in place. Not sure if that makes a difference.