Adding repeaters to your radio
Nearby ham radios are generally on the ham radio UHF and VHF radio frequencies.
Radio repeaters can be heard at the output frequency, but to reach the most distance using the repeater, you must transmit at a nearby frequency (offset listed in the listing). A CTCSS (also called "tone" or "squelch" of the repeater) frequency or DCS code is also generally required on most standard FM radios, or a "color code" on DMR enabled radio for DMR repeaters. When working, many repeaters will respond with audio output, a beep, or message after it finishes retransmission of your audio.
Programming repeaters into the radio
The programming steps on the radio vary from radio to radio, depending on the model:
Programming a Baofeng on keypad
Programming the Radioddity GD77 (with computer cable).
In general you can search for tutorials for "programming (your radio type and model)" to find a video walkthrough.
For step by step instructions even when internet/cell service is down, you can purchase and preinstall RepeaterSTART for easy step by step instructions for a variety of radios:
Programming cable
Depending on the model, you may be able to download software on your computer from the manufacturer or from CHIRP.
Log in to hearham.live and favorite your repeaters, then choose the CHIRP export option to export to a file. After loading the repeater list (also know as "codeplug"), write it to the radio. The memory channels should be usable to contact others using the nearby repeaters.