Encrypted Mail Set Up

Hi,

I would like to send encrypted mail and am trying to set up a Digital
ID.

On using the Wizard, I am having difficulty at the stage where I am
asked to specify a file to import. Can someone advise.

I also note that I have a number of certificates in Intermediate
Certificate Authorities, and Trusted Root ..., nothing in Personal,
and Other People. Can someone also explain their significance?

Thanks
.