Air in master cylinder. How do you bleed now?
 

OK, I forgot and let the reservoir go all the way down to where it allowed air into the MC. Now I am ready to bleed the brakes and get nothing for fluid going through the lines.

Should I bleed the MC by opening up each port at the MC or can I just "hope" eventually fluid will start to move through my lines?

I originally only broke into the front brakes but do I need to bleed all of them even the back?

Thanks,
Ben

You need to "bench bleed" the master cylinder. Yes, basically, you're gonna be undoing the lines affected (our systems are split into two circuits) and place a finger on the ports while someone presses the pedal gently. You let the air squeeze by and out until you get fluid, then re-connect the line(s). I'd google "bench bleed master cylinder" for a better explanation though.

start by bleeding the brake lines, start with the brake furthest from the MC your rear right and then the rear left. make sure you have enough brake fluid in the reservoir with the cap off. Last but not least bleed your MC. once you start seeing clear brake fluid(without bubbles) in the clear line which you are using off of the bleeder nipples you have bled the system correctly.

good luck.

Keep in mind to bleed the MC first, then the lines, or else you're just feeding air into the lines.