Here is a nice and easy video tutorial on exactly how to use the MICVOX Simple Recording Template for FL Studio to record audio vocals into FL Studio on-top of an imported beat. Feel free to download it here.

MICVOX Toolbox for FL Studio
MICVOX is a Simple Recording Template for FL Studio created by SampleSimpleLABS.
You can download MICVOX for FL Studio 9 and 8.
To download MICVOX, enter your BEST email address below for a SampleSimple Subscription
REMEMBER:
You MUST have an ASIO soundcard device driver selected in the Audio Settings Input/Output list to record audio into [...]