Exporting and importing a database
The link below is from oracledistilled.com and goes through Enterprise Manager >> Data Movement.

Clone a Database to Another Host using Enterprise Manager 11gR1 Grid Control

It is very well explained with good screen shots and walks through Cloning i.e. another function under 'Data Movement' >> 'Export Export to File'.

Under host credentials the normal user is the O/S Oracle user, Alex Poole mentioned in a comment:


  Host credentials are for an operating system account (e.g. Oracle). SYS is a database account and has to be connected AS SYSDBA (not as 'normal' in the drop-down role when you log in to EM).