Deep voice

First, let me say that I'm beginner. I have two questions.

1. Should I become really profecient in one lesson before moving onto the next? From what I've seen thus far, we do review previous lessions, but I just don't want to move on to quickly. 

2. I have a very, very deep voice and I find it very difficult to reach the notes that are in the lession. How do I sing in a deper octive and still be 'singing the correct notes or compatible notes? (I know nothing about singing, forgive my lack of correct terminology). 

I'd stick with a lesson until you feel you have a decent handle on the concept, but know that you won't "master" any one technique, even in a few days! Here's some more guidance on using the beginner course: https://www.30daysinger.com/blog/one-lesson-per-day-how-to-practice-for-the-best-results

As for matching pitch, listen for notes in a lower octave played on the piano, rather than sung by the instructor (if it's myself or another high-voiced instructor). I typically play & sing in the upper octave (comfortable for most female voices), but I play one octave lower on the piano (comfortable for most male voices). If you want to keep things simple, male instructors may be easier for you to follow at first! And be sure to download the "bass" warmup mp3's for each lesson, as those should be comfortable for you. 

I'll link some lessons below that may benefit you:

https://www.30daysinger.com/tutorial/how-to-sing-in-tune-for-beginners-part-1/1

https://www.30daysinger.com/tutorial/how-to-sing-in-tune-for-beginners-part-2/1

https://www.30daysinger.com/tutorial/head-voice-and-falsetto-for-male-singer/1