Sometimes it says it failed when there are only warning messages. Did you look at the error message to see what the error was? Did your user id have the role of export_full_database and import_full_database? In Windows
sometimes it is an authentication error because your user id doesn't have permission for "log on as batch job".
After it exports correctly to a file such as D:\expdata.dmp, you go into OEM , select the target database you want to import into, and select IMPORT and list D:\expdata.dmp as the input data and it leads you through the screens to where you submit the job.

Hope this helps.