To create a new PST file in Microsoft outlook 2010Please follow the below steps
1- Open
Outlook 2010.
2. Go to the
Ribbon and select the
Home tab.
3. In the
New section, select
New Items.
4. When the menu appears, select
More Items followed by Outlook data file.

5. When the Create or Open Outlook Data File window appears,
browse to the location where the file is to be located. Go to the
File name text box and input the desired name for the file. If you wish to add a password to the file, check the Add Optional Password check box.
6. Click the
OK button.