There are two options to import the certificates -
Select Import a local end-user certificate with private key from a PKCS#12 (.p12 or .pfx) encoded file.
Next, enter the Certificate Name and the Certificate Management Password (the password you defined when creating the .pfx file). Click Import.
Import a CA certificate from a PKCS#7 (.p7b), PEM (.pem) or DER (.der or .cer) encoded file
Click Add File and browse to locate and open your Certificate .pfx file. Click Import to import the selected certificate.