Hey, so I have been doing the lessons but I don't know and not sure whether to follow the instructor's voice or vocal range from each exercise in the lesson. It's like should I try to follow the instructor's vocal range, even I can't sing at his tone level. Sometimes, when I try to follow and do the exercises like belting, it hurts my throat and I make voice crack every time.

So what should I do?

Hi, Jared! Are you following Jon Statham or Jonathan Estabrooks' course? If you try mine out, you can follow along with the lower pitches I play on the piano (I sing and play in my octave, but I also play an octave lower for tenors and baritones). 

I am currently following Jonathan Estabrooks's course for my foundation singing. Should I just sing what's within my vocal range or try to follow along with the instructor's vocal range, even though I can't reach that note?

Sing what you can! And if you can drop down the octave when he's singing too high, do that!

Okay, thank you, Camille! I appreciate it.

Sure thing, Jared!