The Send an Email action allows you to send an email to those contacts who enter the Journey's funnel. See Fig 1 below. 

Fig 1

To select which email to send, click the Send an Email action node once you have added it to the Journey work area. Doing so will bring up this popup ("Properties") on the right-hand side of the screen (See Fig 2 below):  

Please note that the last three fields will be autofilled based on the Journey's targeted database:

• Send-From Email
• Send-From Name
• Reply-To Email

Fig 2

Clicking the "Campaign" input field below the "Send an Email" label will bring up a list of all your available emails from which you may choose one (See Fig 3 below). Select the email by clicking its name.

Fig 3

Once the email has been selected, the system will autofill the input for (See Fig 4 below):

• Subject

Fig 4

Please note that you may edit the values for :

• Subject
• Send-From Email
• Send-From Name
• Reply-To-Email

Once you have finished with the email setup, click the "Save Properties" button.