To pull out the valve, first twist the top of the valve open counterclockwise to detach it from the rest of the valve.
Pull the valve out of the trumpet.
Near the top of the valve, twist the top part of the screw compartment off to access the screw.
Pull the old spring out and replace with the new one.
Reassemble the valve the same way it came apart.
Before inserting the valve back into the trumpet, put enough valve oil on the valve so that that the surface is wet, but not dripping.
Insert the valve into the trumpet, and screw in the top clockwise.
Be sure to grasp the top of the valve and twist until a clicking sound is heard and the valve locks in place to ensure that the trumpet is ready for playing.