Need to self Inject. Need help.

For around 7 months now I've gotten weekly b12 Injections at my doctors office but she has went on vacation and the other doctors around do not take my insurance. She won't be back for another six weeks but I have the vials I just bring them to the office to get injected. I am super scared of doing them myself and don't want to mess up or hit something wrong. I have no idea where I can buy needles or what else I would need. I am also pretty broke and have no idea how expensive it will be to so it myself. Any advise would be so appreciated.