The purpose of an alias email is that when your inbox is connected to one email, the lead would be seeing the second "alias" email in the "from" field in the email sent out to them (however, their response would still go to the inbox connected to your account. To setup an Alias Email:
Step 1: Make sure the Alias Email is setup within your email account by using the following article:
How to Setup Your Alias Email in Gmail
Step 2: Find your initials in the bottom left hand corner and go to "Setting and Billing"
Step 3: Click on "Mailbox":
Step 4: Scroll down to the "Alias Email" section:
Step 5: Enter in your desired Alias Email information and click "Save" once finished: