Not all machines have filters. if it has one and it's not an obvious flap in the front of the machine it may have one in the waste pipe between the bottom of the drum and the pump, or some just have a trap in the waste pipe that is meant to catch heavy stuff that would block the pump.
To check under the machine first turn off power, then pull it out just clear of work surface and tilt it backwards so it rests back on the edge of the work surface. you can then get underneath and see if there is a filter in the big black pipe that goes between the drum and the pump. if there is undo the clip holding it in and pull it out (water will come out so have a bowel underneath)
if you have no filter in the pipe then chances are your problem is the pump is blocked (the pump is at the bottom end of that big black pipe). you can remove the pump by undoing the two bolts that hold it to the base of the maching, undo the clips that hold on the two pipes and pulling the two powor connectors off (doesn't matter which way round you put them when it goes back on) then you can look inside the pump and should be able to remove anything blocking it.
refit is basically reverse of above.