Heroin can also be smoked. Ask him for crack specifically. Crack is just heroin mixed and cooked with baking soda. Shouldn't be hard for him to obtain if he's already got the hardest part of the process in his possession, and it's easier to not mess up. Just hold it in for 10 seconds, then breathe out, and repeat until overdose occurs.
If you still insist on vein injection then search for your vein, inject at a 45 degree angle, not 90 degrees downright. This is called an Intravenous Injection (IV). Search it up for medical guides, as there are legit uses for IV for normal people like Naloxone administration and prescription drugs for people. Search up what a Vein looks like for better identification. You'll probably go to the hospital if you inject it into an artery. Educate yourself on the basic anatomy or use a picture guide of your arm online to ident your vein.
Do not, under any circumstances, inject the needle if there is an air gap visible. This will cause an embolism that could cause extreme damage and could be a CTB method itself, though painful and unreliable. Do the thing in the movies where doctors squirt a little liquid out and flick it off the needle. This insures that no oxygen bubbles exist. Now inject. You will feel an almost immediate-1 minute delay of a high after injection. If the entire lethal dose is in the syringe, expect to pass out soon.
