How do I add a column to an attribute table. 

When I open up the attribute table, I'm unable to click the edit pencil because it's grayed out.

[![enter image description here][1]][1]


Ultimately, I'm trying to transfer data in a column I have in excel into this zoning shape file.

[![enter image description here][2]][2]

I tried searching for a solution to this issue but wasn't able to find anything.


  [1]: https://i.sstatic.net/PA4mW.jpg
  [2]: https://i.sstatic.net/u7VKn.jpg