If you're using a stereo power amp with the integrated amp, you use standard analogue interconnects from the preouts on the integrated to the inputs on the power amp, and speaker cable from power amp to the bass input terminals of the speakers - having first removed the 'jumper' links on the speakers.
If using monoblocs with an integrated amp, it's the same, except the left and right channels for the bass are in separate boxes.
If using a preamp with two stereo power amps - or indeed four monoblocs - you run interconnects from preamp to one stereo power amp, or pair of monoblocs, and then interconnect cables from the left treble amplification to the left bass amplification, and the same for the right channel. Most power amps have 'dasiychain' preamp-level outputs to facilitate this.
If you have triwirable speakers, you can do the same, but with two stereo power amps plus the integrated, or three stereo power amps (or six monoblocs!) run from a preamp. In each case a separate run of cable goes from each amp channel to the appropriate inputs on the speakers.
Take your time to set all this up, and check and recheck connections are all correct, and with no shorts, before firing up the amps. Getting it wrong can give a horrid sound at best, and damage to speakers and/or amps at worst.