Hi I'm Wayne,
I will help you with this,
If you just replaced the slave cylinder, yes that needs to be bleed, you should have a bleeder fitting on slave cylinder, if not crack the line loose.
Steps to do this, have someone, pump the pedal 8-10 times, hold to floor and crack line loose,, tighten, and repeat this 3-4 times, if it still won't prime, crack line loose and have some one push the clutch pedal to floor, and hold (DO NOT PUMP), and crack the line loose, repeat this step 4-5 times. Making sure your master cyl is always kept full.
If this helped you ,please hit Accept, if not get back to me.