I am assuming you are not very familiar with working on brakes.
If you had the like disconnected at one of the "banjo" fitting, make sure you still have copper washers on both sides.
The bolt has to tight, but not too tight or it will strip or break.
Look up the proper torque for the hollow banjo nut here
In the Blaster Manual.
(in fact the whole procedure is in the manual)
If you do not own a torque wrench, you really ought to buy one.
Torque wrenches are REALLY important for those who have never owned one.
OK, line on, copper seals on both sides of the line, bolt just the right tight,
now you have to bleed the air. Fill the master cylinder, loosen the bleeder nipple.
Pump the brake and hold it. Air or fluid will come out. Snug the nipple, let off the brake lever.
Pump the brake and hold it. Air or fluid will come out. Snug the nipple, let off the brake lever.
Do this until no more air comes out. Snug the nipple, you are done.
If this doesn't work, get back to us.