It's not hard, the SReject has already provide some examples in his JSON script of how can you do that but anyway, you can add more by your own it's easy just follow this example:

NOTE: Make sure that you are using the latest mIRC version and the latest JSON script addon version.

Code:
alias get_results {
  var %v = res_ $+ $rand(1,100000)
  var %u = http://maxima.e-sim.org/apiCitizenByName.html?name=dazzler
  JSONOpen -ud %v %u
  if ($JSONError) { echo 4 -a Error: There was an connection problem! - (Error Details: $jsonerror $+ ) | return }
  var %str = $json(%v,strength)
  var %rank = $json(%v,rank)
  echo -a Results are - Strength: %str - Rank: %rank
}

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