You can send out a new email by pressing the "New" button on the top left of the screen, to the left of the search. Every page has this button available.
Once you click "new" it will open up a dropdown menu with the available options to you.
To send out a new message you will need to click "New email". It will take you to a new page
You will need to fill in all the mandatory fields marked with the red star at the end of the property name.
It is important that you select all details correctly or to use a correctly pre-created Template to fill all the details for you.
By default the priority of the new emails are "low" which is not correct for as everything should be Medium by default and high priority cases should be Urgent priority.
The status is by default closed for new emails, make sure you change it to the correct status to reflect the status of the ticket is currently in.
If you are unsure on what to select for type/priority, you can check the solutions tab of the customer, the "Category and sub type mapping"
When you select the group, it will change the From Email address to the one that is assigned to the group selected.
Once you are ready to send the email out, you will need to hit the "Send" button on the bottom.
If you check in the Send another checkbox then after you click Send it will not redirect you to the sent out email ticket page but will keep you on the new email page with an empty email.