If you are a citizen of a country outside the EU, you will in most cases need a visa. List of the countries which need a visa.
General information on how to apply for visa can be found at the Migration board.
In case you need a visa, then you need, among other thing, an invitation to the conference. Participants who registered and paid the registration fee may apply for a Letter of Invitation by emailing Lisa Knutsson, email@example.com. The request for Letter of Invitation should include
- Your personal data
- The reason for your visit to Sweden
- How long you intend to be in Sweden
- Who will be responsible for supporting you financially during the time you are in Sweden