If you tell us make and model, you may get a better answer. The instructions may have a better answer too.
After you swtch-on the unit -- change the channel to a channel that has been chosen by your group to use...
Good instructions, when I teach how to use radios, the biggest problem I see is people forgetting to release the PTT button in order to listen. Push To Talk (PTT) Release To Listen! While we call them two way radios, they are one way at a time. Enjoy!