While it's not essential for sending emails through Salesforce, it's good practice to create and re-use email templates. These steps will show you how to create a template.
We'll find our way to the Email Templates in Salesforce by clicking the 3x3 grid
Type "email"
Click "Email Templates"
Click "New Email Template"
Click the "Email Template Name*" field.
Type in a name
Click "Related Entity Type"
Click "Application"
Click the "Description" field and type a description
Give your email a Subject.
Type out your email template
Click "Save"
Next we'll send a single email to a participant. Navigate to their application record.
Click "Write an email..."
Next we'll insert our template. You could alternatively type out the email here.
Select the template
Make any changes to the email. You can overwrite the template by selecting the option to save it where you inserted the template.
Click "Send"
The record of the email is saved to the application record. Salesforce also automatically sends you a copy of the email in case you need it in Outlook.