You can find out if you need a visa to visit Germany at the Federal Foreign Office ("Auswärtiges Amt" in German).
In case you need to apply for a visa you need a Legal person's invitation letter form sent by the local organizer. To get that form, the company/institution of the applicant has to provide guaranties to cover all possible costs if necessary (including health care, etc.).
To send a request for the Legal person's invitation letter form please follow these steps:
You can email scanned copies of the signed guarantee letter and the reservation confirmation or fax them to the Euromicro Office.