If you're talking about the PLCs.net PLC simulator: go there and click the 'help' menu option.
Please be more specific in your posts. With over 100 different brands on the market it's difficult to give a good answer if you don't bother to give us at least some details about brand and type of the equipment you're inquiring about. This post for one is far to general to give any meaningfull answer whatsoever.
BTW, it doesn't hurt to say please from time to time.