How to make sticky call to action button in shopify

[CocoaJoes]

my website is Order Fresh Cookies Now – CocoaJoe’s (cocoajoes.com)

I am trying to make a sticky order now button that is visible on every page but the shop page that sticks to the bottom left of your screen and when you press it you are brought to the shop page.

[CocoaJoes]

I did in the op its, cocoajoes.com