Not Sure How To Edit Index Page

Hi there I trying to find out where I can add keywords and a meta description to the home page of this theme. I am using the Yoast SEO Plugin and can add these to every page except the home page.

Zerif Light reads this page as my home page http://myrankseo.ca/what-we-do/ not the index page itself. There is no place to edit the index page anywhere except in appearance where there is no option to add keywords or a description.

Right now in Google my search description is the first paragraph of my website text which I do not want. It also doesn’t have any keywords included in the proper places.

Any help would be appreciated very frustrating thanks:)