Speaker mic plugs into radio (many radios have silicon cover which lifts to unveil jack). Press push-to-talk button while speaking and let go to listen.
Recommended location to clip speaker would be on upper body/shoulder area while leaving radio attached to belt. Placing speaker in this location will improve ability to hear incoming communications. Keep in mind that this can get loud (based on radio volume setting) and is not private.
Make sure to turn ON radio prior to connecting speaker mic (if you do not it may force broadcast which means other radios on same channel will be in use as if you were pressing the push-to-talk button).