Step 1: Go to Apple support website and click 'Set up a repair'
Step 2: Select the category your Apple product falls under
Step 3: Pick the category of issue you are facing, e.g. 'Hardware issues' if your keyboard is not working properly
Step 4: On next screen, select specific hardware issue, e.g. 'keyboward is not working properly'
Step 5: Select the method of communication you would prefer
Step 6: It will ask you to provide serial number along with name and email address. You can find serial number by clicking on Apple icon (at top left corner of your desktop) and then 'About This Mac'. Note down the serial number. Also write down OS name and version because support engineer may ask about this during conversation.