you can apply for a temporary valid license in a German citizen center or town hall (valid 6 months). This can be prolongate for another 6 months.
Then you have to pass a German driving license exam (theory and practice). You don't have to do a special training for that, just register for a driving license exam at a driving school.
For short information see http://bit.ly/1tc2z5r
(German text - Google translation)
For details see http://bit.ly/1tc2tKR
(very detailed, German text - Google translation)
Kind regards, Jan