If you have OST to PST files and want to convert them manually then, let's understand how this method works by following some steps:

1. Open the MS Outlook in your system.
2. Click on the file tap and select and choose the export option into PST.
3. Now, select the emails to export.
4. After that, Export OST files to PST.
5.  Wait for completing the process and the Outlook Profile will be saved to PST file format in your allotted location.

As you saw, the Manual method is a time-consuming process it doesn't ensure data security and is always prone to errors. If you want to error-free and safe conversion then go with DRS OST to PST Converter. Using this tool you can easily convert OST to PST and other several formats. This tool ensures your data integrity and security. It has a simple and smooth GUI that makes the conversion process hassle-free.