Hello and app store registering

Hi,

i've arrived from Windows world to Macland and it's all new but I'm having a pretty good time so far.
I'm using a new macbook with Snow Leopard and have set it up as best I can so far, firewall activated etc.
I have also installed Sophos antivirus (don't want to start a discussion on this, I know it's a contested subject but coming from Windows it gives me peace of mind)
Only one question so far, when I click the App store icon and go to create an Apple id the little lock appears on the browser to say its a secure connection but how do I know its secure?
There's no https showing and no certificate is given so how can I check?
Probably a naive question but I'd like to know how it works rather than just blind trust, not that I've brought any Windows paranoia with me or anything

 

I assume that it's Safari or linked in to it.
I click on the App icon in the dock and it launches and that's it.
Same as if I click on the Itunes icon and go to the Itunes store.