tatt, take a look at this www.exrx.net/FatLoss/WT%26End.html
It explains why doing resistance/weights aswell as CV is going to shift the weight. So doing 15 mins CV and then 15 mins weights will shift the weight better than just doing 30 mins CV.
You must have a rest between weights so doing 5 upper body weights one day and then 5 lower body weights the next session is a good idea as your muscles need the time to repair and grow otherwise if you dont let them rest you will not allow them to repair and grow. Plus you must feed them - eating after your work out some protien and carbs is a good idea.
A pound of muscle uses 106 calories in 24 hours a pound of fat uses 5 calories in 24 hours
So get them to show you how to use the machines - start with perhaps 5 machines at first and a low weight, move the weights slowly, about 10 seconds one way and 14/15 seconds back - this will build the muscle you want to tone up.