To create a new PST file in Outlook, follow these steps:
Open Outlook and click on the "File" tab.
Click on "Account Settings" and then select "Account Settings" again.
In the "Account Settings" dialog box, select the "Data Files" tab.
Click on the "Add" button.
In the "New Outlook Data File" dialog box, select "Outlook Data File (.pst)" and click "OK".
Choose a location and name for your new PST file.
If desired, you can also set a password for the new PST file by entering it in the "Password" and "Verify password" fields.
Click "OK" to create the new PST file.
Once you have created the new PST file, it will appear in the "Data Files" tab of the Account Settings dialog box. You can then use it to store Outlook items such as emails, contacts, and calendar entries.