The people on the other end can’t hear me

Are you sure the mike is working? Do they hear the click of the Mike button pressed?

Make sure they are monitoring the correct channel as different radio's use different bands as an example CB vs Ham. So make sure they are using the same bands and channel.

How far are you from them? Are you using the radio as a base station or is it in your vehicle? Have you ever been able to talk to anyone before? What type of antenna are you using and how long is the coax? How high up is the antenna? Is the coax 50 ohm impedance for radio? Do you hear them clearly? CB radio can be very particular at times and weather affects it. If you can hear them, you are likely on the correct mode (AM, FM, or SSB). AM is the CB default but SSB has been a long term option and in recent years FM has been added. Try starting with a known contact that is close and then when you know it works you can try farther.