I have gone through same testing, but with a german airline. They will just use the sim for VERY BASIC manouvers. Such as alt hold climbs and decends. Also they might do some time orientation excercises such as fly heading 300 for 30 seconds then climb 2000 feet after another min then turn right 340 and keep that heading. all without a clock. they test your motor skills such as multi tasking etc. you wont need to know any of the systems itself as you are a beginner. Set up fs and do some basic turns at 30 Deg and 10 and 20. and pratice some basic climbs. also speed is important. but these are all very basic things that mostly anyone can do.. the question will be how well you do them. We were also set up on a pulse monitor to see how we react in the stress situation.
All the best. and if you have any question about the 737 dont hesitate to ask.
luke