-there will be zero brake pressure with the brake resivoir open first of all. (assuming it was because you said you saw bubbles)
That is not true.
jwinkler, do you know what it means to bleed the brakes?
With the reservoir filled, you'll need a hose on the bleeder valves on your calipers that goes to a container. Then you'll open those bleeders with a wrench and pump the brake lever until fluid comes out of the bleeder, through the hose you attached and into your container. Then close the bleeder.
Careful when you pull the lever, it can squirt fluid out of the reservoir and onto your bike. This stuff is caustic, it will eat paint. Maybe set the cap on the reservoir while pumping the lever. But make sure the level in the reservoir doesn't drop low enough that it can suck in air.
You'll need to repeat this for the other caliper as well.
Once you have the brake lines filled, you'll pump the brake lever until it builds up some pressure, while holding it in, open the bleeder fitting and let the air bubbles out. You'll close it again before all the pressure at the handle is gone. You'll repeat this process many times. It'll help to have an extra set of hands around.
When I did it I couldn't get all the pressure needed by this method alone. That's when you do what Slim mentioned. Pull the lever in until there is a lot of pressure, tie it to the bar, and lit it sit overnight. This firmed mine up immensely.