Check your Beats model (wired or wireless).
For wired Beats: plug the headphone cable into the iPhone headphone port or a Lightning/USB-C adapter (if needed).
For wireless Beats: turn on Bluetooth on your iPhone Settings > Bluetooth > On.
Put your Beats into pairing mode (press and hold the power/pairing button until the light flashes).
On iPhone, open Settings > Bluetooth and select your Beats from the Devices list.
Tap Pair if prompted.
If using Beats with the W1/H1 chip: bring the Beats near the iPhone and follow the on-screen pairing prompt.
If connection fails: turn Bluetooth Off/On, turn Beats off/on, and repeat pairing mode steps.
To connect later: Settings > Bluetooth > select your Beats, or use the Bluetooth menu in Control Center.