External USB Drive Outlook Data

Hello - Great software and much more than OutLook.
I have an external USB Drive with lots of folders and data I use with Outlook.
How can I configure eM Client to access all that data on the USB Drive please? Have not been ablt to locate the process.

If the file is an MS Outlook PST file you can’t just open it, but you can import it into eM Client using Menu > File > Import > Outlook Data File.

Thanks for the speedy reply Gary.
Vary smart software with lots of functions have never seen before and will become useful as I get to understand the software more.
I did not explain myself very well.
Ewitj Outlook I only keep emails I have yet to deal with on the Data file on Drive C:, and I move the sent and received of each matter to the external USB Hard drive when complete.
That way, I have history mail on a separate mail – because Outlook keeps ‘crashing’ and I don’t lose history.
My external drive has thousands of files of history on it - about 10 Gb).
Is there a way to import into one folder in eMClient, then copy that oner onto a Hard drive and still have access to the hundreds of folders I have on my current external drive?