You must apply for a Schengen visa for a period of up to three months (90 days) to enter and stay in Germany. If you think you should stay in Germany more and / or work, you must apply for a permit called “Residence Right” Residence title).
German visa for staying less than three months
You need an airport visa or airport visa if you want to have a short stay (though for a few hours) on your way to a destination other than Germany at one of the airports in this country. With this visa, you can only enter the international airport of Germany.