If a mixer has "monitor out" jacks (yours does not), just buy plugs/cables/adapters that fit those jacks and match your speakers.
If you want to use the mixer's line outputs (yours has 1/4" jacks for this), just buy plugs/cables/adapters that fit those jacks and match your speakers.
Another method is to connect the speakers to the "headphone output" (you can then control the level with the headphone volume on the mixer).
To do this, buy a cable that has a 1/4" stereo plug on one end and the other end splits to two RCA plugs.
Buy two adapters for the RCA ends that change to 1/4" to fit your speakers.