Thunderbird is a mail application like many applications e.g. MS outlook and you can configure it to be your default mail application.

Here are simple steps to setting up Mozilla thunderbird.

1. Download the application from the website. https://www.thunderbird.net/en-US/
2. Double click the downloaded application to install it.
3. Once the installation is done, launch the application to start
4. Once the application starts, it will prompt you to set up an account or continue with the existing account.   
5. Fill in the full name, email and password
6. 
7. You will be prompted for manual configuration as follows

9. On the server information, enter the following information and click next.

Select IMAP.

Incoming mail server: Hostname of your server eg sbg106.truehost.cloud

Outgoing mail server: Hostname of your server eg sbg106.truehost.cloud

10. Enter the email address as your username
11. Account name enter webmail and click next
12. You’ll get a summary of all your settings
13. Click finish
14. Thunderbird will connect to your mail server and it prompts you a password, enter your email password.