If you already finished your studies (outside Germany), your first step should be the recognition of your certificates: www.anerkennung-in-deutschland.de
Make it in Germany (www.make-it-in-germany.com) is the official portal welcoming international qualified professionals to Germany. You will find information about living and working in Germany as well as about immigrating and career prospects.
The european employment service EURES provides further information about living and working in Germany as well as extensive information and advice that can prove helpful for everyone who wants to be mobile in the european job market.
In the database jobboerse.arbeitsagentur.de of the German Employment Center you can search for job offers.
Further databases for permanend or seasonal jobs