Put both earbuds in the case, lid open.
Hold the button on the back of the case until the light flashes white.
On iPhone: Settings → Bluetooth → Surface Earbuds.
Not showing up? Tap (i) next to it in Bluetooth → Forget This Device, turn off Bluetooth on any other device they were paired with (like a PC), then retry. If that fails, hold the case button about 10 seconds to reset, then pair again.