Link redirection to a category!

Hello,
I am trying to redirect a link on my website to go directly to a category.
http://mech-fab.com/beta/portfolio/
What I am trying to do is send a link directly to one of these categories without showing the “Show All” option first. My problem is that the URL is the same whenever I change categories. I would love some advice on how to get this fixed.

P.S.
I am very new to wordpress, I’ll try to keep up, but go easy on me.