Starting insulin

So I just picked up my prescription of Lantus insulin for the first time as a newly diagnosed type 1 diabetic and I have a few questions before I jump right in. Unfortunately my doctor's office is closed until Monday morning, and I don't personally know any other diabetics that take insulin, so I come here to get any info I can 😅

First of all, my prescription didn't come with any needles as I thought that it would, so I assume that I need to go to a pharmacy and purchase those?

My doctor said that I am supposed to be taking 10 units/mil of the insulin once daily. When would be a good time to take that? Morning or evening? And where do you usually inject it? Upper arm or stomach? Also, how should I dispose of the needles after use?

I've never done this before, so I have no idea what to expect. I am just so nervous and am trying to learn, but it all seems so daunting, so I am open to any and all information/tips that y'all can give me. TIA!

Edited to correct the dosage. 10 units once daily