If you received a Form 1099-MISC instead of a Form W-2, the payer of your income did not consider you an employee and did not withhold income tax or Social Security and Medicare tax. This income is considered self-employment income and you must complete Schedule C (or Schedule F) and Schedule SE.
To enter or review the information from Form 1099-MISC, Box 7 Nonemployee Compensation:
You do not necessarily have to "have a business" to be treated as a self-employed worker. Simply performing services as a non-employee can be enough to create this tax treatment. See Employee or Independent Contractor for more information on this determination.