Plug the modem in. It scans the frequencies and locks on. If it doesn't. There is either a signal problem or the modem isn't authorized on your account properly.
The auto scan is part of the DOCSIS standard the modem is built to. EVERY cable modem does it.
If yours doesn't, it'd be the first I've seen in the thousands I've hooked up over the last dozen or so years.
I've seen modem with the option to put in the initial frequency to scan but I've never seen it needed. I've used to shorten the scan times back when Motorola 2100 modems took 30-45 minutes to scan and sync, but than was 10 years ago
Anyway the lowest scan frequency. Is 54 MHz and the highest is 1000 MHz. The channel spacing is 6mhz.--
If it's important, back it up... twice. Even 99.999% availability isn't enough sometimes.