Questions about Harman/Kardon Hkts 210 Sub

I bought the Harman AVR 171 S cardboard box from you last week and would like to know which subwoofer and speakers would go with it? Subwoofer for example HKTS 210 SUB ( 200W, subwoofer). How does the power rating of 200 watts compare with the AVR's power rating of 100 watts? If I were to buy an active subwoofer, does it have a connection for it on the unit. I assume that in this case the power rating of the AVR is not relevant.