From the instructions with my SWR meter:

1) Set CALIBRATION/FS/SWR on the front of the meter to CALIBRATION/FS.

2) Turn on your radio.  Then select a channel or frequency on your transmitter and hold down its transmitting key.  Do not speak into the microphone.

3) While you hold down the transmit key, rotate the meter's knob until the needle points to CAL.

4) release the transmit key, then set CALIBRATION/FS/SWR to SWR.

5) Press the transmit key again, then read the SWR by noting the needle's position on the upper SWR scale.  A meter reading of 1 on the upper scale is ideal.

6) Repeat steps 1-5 for each channel or frequency you want to get an SWR reading for.

NOTES:
An SWR reading will be different for different frequencies (channels).  If you transmit on one channel more often then any other (we frequently use channel 10), select that channel.  If you transmit on several channels, choose a frequency in the middle of the range of channels you use.
If you use a CB that has sideband modes (SSB), do not select any of these modes.
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My instructions do not indicate how specifically to adjust the antenna - refers to manufacturer of the antenna.  But it does caution that a small adjustment (1/8") can make a measurable difference. NOTE: if you have Jeff Anderson's antenna splitter you can adjust the potentiometer by turning the adjustment screw (no actual antenna adjustment needed).

Hope this helps.
Tom