Make a SideBar on Left side of page

Hi Guys!

I would like to have a skinny sidebar on the other side of my pages. 125-150 pixels optimally.

Don't mind if I have 1 post per row, with a bigger image and more text displayed, if that needs to be altered to accommodate.

There is a lot of empty space surrounding my site...Is that fixed/unchangeable?

Thank you so much!!