If you can travel to Germany without an entry visa, and/or have only a limited residence permit, you must reapply for and receive these in Germany within the period of stay permitted, from the local authority for foreigners covering your German residence
As a rule, to enter the Fedeal Republic of Germany you need in principle a visa.
Generally excepted are citizens of the EU countries, as well as other countries for which the European Community has abolished the visa requirement for short stays of up to 90 days within a period of 180 days.
You can check here whether you need a visa, on the official link of the Foreign Office of the Federal Republic of Germany:
Responsible for the granting of visas are the Embassies and Consulates General (diplomatic missions) of the Federal Republic of Germany.
Locally responsible for the processing of visa applicatons is the diplomatic mission within whose area of jurisdiction you have your usual place of stay or residence.
Since, as a rule, the taking up of employment lasts longer than three months, you need a national visa!
For your application for a visa, you should have ready the following:
For long-term stays you apply, In most cases, for a National Visa
For short-term stays up to a maximum of 90 days you can apply for a Schengen Visa
Important: Please bear in mind that if you choose to get a Schengen Visa with a plan to stay longer in Germany, you have to get the extension of your visa before expiration of the 90-day period