How do I get the harmonic balancer off my ford ranger, to replace it?

Use a puller designed to remove a crankshaft damper. Such a puller has bolts that screw into the pulley bolt holes in the center hub of the damper. Do not use a gear puller or any puller that grips the outer circumference of the damper. Such a puller will damage the damper.

Getting the nut loose is yet another problem. An impact wrench or (but be carefull) wedgeing a breaker bar with an impact socket on the nut and lightly engage the starter. Socket wrenches easly break. So do normal sockets. Use only a 6 point socket to avoid rounding the bolt. They are torqued likely at 120 ft lbs and are a PITA to remove.

See if this helps:

. Remove the driveplate access cover and hold the ring gear teeth with a large screwdriver or pry bad, to prevent the crankshaft from turning.
. Remove the nuts that secure the pulley bracket to the engine front cover. Remove the pulley and bracket from the engine.
. Remember, the crankshaft pulley screws into the crankshaft damper with a left-hand thread; turn the crankshaft pulley clockwise to loosen and remove it.
. Remove the crankshaft damper retaining bolt (it has conventional, right-hand threads).
. Using a suitable puller, remove the crankshaft damper.