When I had my Katana, 90% of the time I had it on the Clean setting with the Blues Driver booster setting.
The clean setting on the Katana is pretty good, and it dirties up a little if you turn up the gain, even without a booster.
Then you can turn up the booster setting to add more dirt. As I said, my preference was for the Blues Driver, which is the green setting, but I don’t tend to go for high gain tones that much.
Then adjust the booster level and gain to suit
For EQ I would start with the bass, mid, and treble knobs at 12 O’clock and tweak from there.
Personally, I tended to turn the bass down a bit, leave the treble at midway, and adjust the mids up and down depending on whether I wanted mid boosted or scooped.
But it also depends a lot on the type of guitar you are using, as well as the acoustics of your room.
That was then my baseline tone, and I would store that in a patch and use that most of the time.
Then I also had a clean tone which was the same setting but with the booster turned down or even fully off.
Start with something like this and tweak the gain and EQ and you should be able to get some great tones.
Of course you will probably want some reverb too.
There’s plenty more you can do from the top panel controls without plugging in a PC, but I would leave that until you feel ready to explore it and are comfortable with getting the basic tone you want.