First, I recommend you to look at user's manual - although it's not complete, you may found some useful information there (at least data collection part is complete).
Also, I recommend you to install agents on your servers - it will simplify configuration. For sample step-by-step configuration of collecting parameter from server and setting up alerts you can take a look at https://www.netxms.org/documentation/confexample/ (a bit outdated, but still valid). You can found list and short description of all parameters provides by agents here: https://www.netxms.org/documentation/common_parameters.html .

And feel free to ask if you will have any problems (but remember - more specific questions can be answered faster and easier  )

Best regards,
Victor