The blister on my heel pop said there's pus coming out of it what do I do to keep from getting infected?

If there is pus... It already is infected. It needs to be drained and cleaned for the infection to go away. If it spreads into the deeper tissue, you will need to take an antibiotic to get rid of it. Use warm water soaks with some epsom salts, dish soap, or even a splash of vinegar (most bacteria aren't that tolerant of an acid environment). Keep the pus draining out of the hole that's already there.
Local treatment. Apply over the counter antibiotic ointment and a band aid to keep your shoe from rubbing the blister. Do not pick at it. If drainage increases or you have red streaks or fever or other signs of infection, see your doctor.
Soak in salt water. Apply neosporin and a bandaid. If no better see professional care.