TRNSYS User,
Without any more details about what you are having trouble with, we really can't answer your question. But for the sake of completeness let's try and we'll assume you need a wet cooling tower:
1) Drag out the cooling tower model
2) Hook up the connections to the weather processor and to the source of the hot water which you want to cool.
3) Set the controls to operate the fan for the tower
4) Connect an online plotter and watch the outlet temperatures from the tower.
Next time, please take some time and describe where you are having problems or you probably won't get anyone to take their time and respond to your question. Everyone here likes to help but only when users take some time to describe where they need help. This is like the situation if something was wrong with my car and I went to someone to get if fixed and simply said. Please fix my car - with no other instructions...
Jeff