How to make a video tutorial on mac

I need to make this first video tutorial of an audio tracker im working on, for later upload to youtube, but there is this problem im having with the audio, i was already able to record the mac audio or "what u ear" with the soundflower app, but i need an duo audio record, i need also to record my microphone simultaneous, is this possible?

 

i have this issue regarding iMovie and...

It happens that the mac book i have was purchased in 2nd hand, and garageband and iMovie aren't available in my apple account, they say i have to purchase them, right?