Having problems with the clutch in my 1998 Ford Ranger. There is no freeplay, and it is very difficult to shift. Do I need to adjust the clutch? If so, how do I adjust it?

The clutch is not adjustable,it is a fluid clutch.It has to be a leak,or the slave cylinder,and,or, the master cylinder are bad,It does not have to be leaking to be bad,but it is one of the two.Rate please,thank you.

The clutch is 'self bleeding' by slowly depressing and releasing the clutch pedal 15 or 16 times according to the service manual I read. It could be difficult to shift because the clutch is not fully disengaging.

Check fluid level if possible.
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The slave cylinder could be leaking and the following can explain what it might take to fix it:
Slave Cylinder Removal & Installation To Remove:
Typical clutch assembly with internal slave cylinder

1. Remove the transmission. NOTE: Examine the clutch housing for traces of brake fluid. If fluid is present, install a new clutch slave cylinder.
   
2. Remove the clutch slave cylinder.
3. Examine the clutch slave cylinder looking for a damaged or worn boot, a damaged or worn bearing, or leaking fluid.
4. Examine the clutch release bearing for damage or wear by turning the outer race while applying pressure. If it feels rough as you turn the bearing, install a new clutch slave cylinder.

1. Install the clutch slave cylinder and bolts onto the transmission. Torque to 15 ft-lb (20 Nm).
2. Install the transmission.
3. Depress and release the clutch pedal 5 full strokes.