Automation Email

I'm creating a automation for a sheet. When someone fills out the form associated to that sheet, we'd like it to automatically send an email to them. I created a automation workflow, and I set the Trigger to be "When rows are added," and then set the Action to "Alert Someone," and then set it to "Send to contacts in a cell" -- and I was thinking it would give me the option to choose a column that has the new email of the person who filled out the form. Yet when I want to use the dropdown of "Select a contact field," thinking that I'd choose the email column, it doesn't give me any option at all. What am I doing wrong?