Wise0ldMan
Hi there. If you buy a non adjustable fiberglass whip they are pre-tuned and normally do not require any adjustment if they are installed over a good ground plane surface. That is your easiest option.

kj7gs
You don't need the little antenna that goes with the SWR meter. The little antenna is for measuring field strength, not SWR. You will need a small jumper cable between the CB and the SWR meter you currently have. Connect the jumper to the "CB" side of the SWR meter and to the CB antenna input. Connect the antenna to the "antenna" side of the SWR meter. Channel 19 is at the center of the CB band, so unless you are tuning for a specific channel, tuning the antenna to that particular frequency will give you a reasonable SWR curve for the band. You do this by checking SWR on both ends of the spectrum. Start at Channel 1. Switch to "CAL," press the microphone Push-to-talk and use the dial to move the needle to the end of the red marking (not beyond that). Release the PTT. Switch to "SWR" on the meter. Press the PTT again, and observe your SWR reading. Now switch to Channel 40 and repeat the procedure. If the SWR on Channel 1 is lower than the SWR found Channel 40, then you need to trim the antenna by a small amount, perhaps a quarter inch or so. This is usually done by loosening a set screw and pushing the whip down toward the coil, for a base loaded or center loaded antenna. If Channel 40 is lower than Channel 1, your antenna whip needs to be longer. This is why antennas are sold with slightly longer whips rather than shorter ones. You either cut to shorten, or buy new if you've cut too much off. However, there is some wiggle room with the set screw holding the whip in place. Short answer, you have to buy a meter if you want to calibrate your antenna.

T H
short answer you HAVE to have a SWR meter to adjust the antenna to it's resonant length what would be ideal, is to make a little antenna to fit the meter you have now (it's called a Field Strength Meter) - AND borrow or buy a SWR meter and use BOTH meters at the same time while adjusting the antenna SOMETIMES if the 2 diodes in the SWR meter are not a "matched pair", the 'real' SWR is not what the meter indicates - so if you use the Field Strength Meter AND the SWR meter to keep the SWR indication below 2.0:1 AND watch the Field Strenght Meter for maximum reading, then you have the best match between your radio and your antenna. the only alternative is to have an antenna that does not require matching (like most of the marine CB antennas) - or better yet, a 9' steel or fibreglass whip, which are the VERY best antennas you can buy