What is required to visit my girlfriend in Germany from South Africa?

There's a really great post on it on travelstart.co.za:

You'll need a Schengen visa, as you're on a South African passport and that's what the Schengen-Zone countries dictate for South Africans (I'm also a South African, but fortunate enough to have a second passport from New Zealand)

The main points of requirements for a Schengen visa:

• 1 filled out application form, signed by the applicant (see next section for form)
• permanent passport – valid for at least 3 months from your date of return from your trip
• 1 recent passport sized photo
• 3 months bank statements
• Letter from employer/academic institution confirming employment/enrollment and when you are due back. If self-employed, confirmation of VAT registration showing you as owner
• Copy of confirmed and paid return flight ticket and documents showing further travel within the EU
• Proof of confirmed hotel reservation and €40 per day in forex or available on credit card OR a formal obligation document issued by the local municipality from the person who is hosting you in Germany , ie friend or family (must be original)
• Proof of previous trips to the Schengen Area (visas)
• Travel insurance covering at least €30,000 for hospitalisation and repatriation

So since you've not been before, some of this should be easier (eg proof of previous trips). The trickier part is the obligation document from your girlfriend's municipality.

Depending where in South Africa you are, there are a few places you can apply for this, detailed on the page, as well as the relevant forms. You'll likely need to make an appointment to visit these places in person (hopefully that's feasible for you).