Sorry to hear about your friend. That's tough.
We generally do not allow non-trained/non-certified personnel to join an ongoing search, for their safety and ours. First rule of SAR: do not turn one rescue into two
Here in NM, you apply to join a SAR Team. Every SAR volunteer in NM must pass the State Field Certification, which consists of 1) a "pack check"; you must show that you own the required equipment 2) show some simple map/compass skills and 3) a written test. Once you have joined a team and passed your Field Certification, most teams have list of "core competencies" that you must acquire. My team for instance require map/compass and GPS navigation, snowshoe skills, basic search techniques etc. etc. Once your team mentor confirms that you have all the skills and equipment necessary, you are put on the "calling tree" and are eligible to respond to "Missions". In NM the SAR volunteers function under the Dept. of Public Safety and the State Police, who will initiate a Mission and start the "trickle down" activity that eventually leads to you getting a call at 2am
Clearly it's not possible for every team member to respond to all call-outs, but we respond as best we can.
In order to remain "Active" and on the calling tree our team requires each member to participate in a minimum number of team meetings, team trainings and missions each year.
It varies a lot how much we are called out - it was fortunately very quiet over the holidays, but in the month or two leading up to the holidays we had 4 or 5 call-outs.
I would certainly encourage you to look up your local SAR team. I know we are always looking for new members. And the needed functions are so varied that we can find a role for everyone: ground-pounders (that's me), communications, base support, transportation, 4-wheel vehicles/drivers, dog handlers and so on.