Update README.md

README.md

@@ -17,7 +17,7 @@ or as a package from your GNU/Linux distribution.
 
 
 **Before** connecting, you need: 
-	- A X509 certificate file.
+	- A X509 certificate file (`*.pem`).
 	- The IP address of the server.
 	- Your username and password.
 
@@ -35,6 +35,7 @@ or as a package from your GNU/Linux distribution.
    append `:5950` to it. So, the `VNC server` entry should look like
    this `XXX.XXX.XXX.XXX:5950`.
 9. Click `Connect`.
+10. When at the login screen, ensure you are using the `Xfce Session` (settings wheel, bottom right) before entering your password.
 
 ## Using Environmental Cheminformatics Programs