Login to your cPanel account. You can log in to the cPanel by referring to the KB here.
Click on Email Accounts under the EMAIL section.
Create a group email address for example "testgroup@readyspace.com".
Go back home and click on Email Filters under the EMAIL section.
Select your group email address and click on Manage Filters.
Click on Create a New Filter.
Input a filter name
Under the Rules section, choose To and contains then type in your group email.
At the Actions tab, please select Redirect to Email then add email address that you want to put into this group. You can add multiple email addresses by clicking on the + button.
After you input all the email addresses, click on Create.