Changing "Portfolio" Permalink

Greetings all. Pretty new to this, so bare with me.

I’m wanting to change every instance of “portfolio” (taxonomy, post-type, etc) to something else, but I have no idea what re-write code to create, or where to place it.

Can someone shed some light on this?

I’m using this theme, if it helps:
http://www.mojo-themes.com/item/diy-multi-purpose-responsive-wordpress-theme/

Thanks for your help!