The type of visa you will need depends on what type of business you will be conducting in Germany. If you are starting up a business, in most cases a Schengen Travel Visa will be good enough. The Schengen Travel Visa is a business visa that let's you conduct business in Germany for up to 3 out of every 6 months. One of these will generally be required for all non-European Union nationals but there are exemptions made.

To apply for the business visa you will generally need

1. A letter from a German business partner inviting you to the country
2. Employment documentation and certification for you salary
3. Documentation of travel health insurance
4. If you work for an employer, a letter from the boss documenting the reasons for the visa
5. If you work for yourself, you may need bank statements and other such documents
6. Valid passport that will stay valid for the duration of your stay in Germany

If you need to stay in Germany for more than 3 months you may need to get a national visa (permit for the purpose of self-employment). This will allow you to run the business on site. If you invest over 250,000 Euros in the business you will likely receive them. If you are a highly qualified professional you are also likely to receive one.

You can file you applications at the German Embassy or German Consulate.