First take a visual inventory of all smoke detectors within your house to ensure the number and proximity comply with safety codes in your local municipality. Then always check your smoke detector manufacturer's testing procedures/manual.
On each smoke detector locate and press the test button. An alarm noise or *light indicator should appear. If it does not test properly remove the cover by turning it or releasing tabs. If the unit is battery powered replace the battery and retest (make sure your battery contacts are correctly aligned positive to positive and negative to negative). If your unit is hooked into your home's main electrical system, ensure that your main electrical system circuit breakers are in the ON position if you are not rewiring or performing other hands-on maintenance. If you retest at this point and the unit is not operational replace it with a new one. Be sure to have the electrical circuit breaker for the unit in the OFF position if you are replacing the unit. Always consult your specific fire alarm system manual or manufacturer documentation.
* Read your manufacturer's smoke detector manual to make sure a light indicator is all that's needed in test phase. Most smoke detectors will sound an alarm during a test.