Hit STORE once and choose a location with the data wheel (either overwrite a user preset or choose an empty location if there’s one available).
Hit STORE again and change the name if you want to (use the data wheel to change the character under the blinking cursor and the arrow keys to move back and forth between characters. If you move too far to the left, you will be sent back to the “choosing location” state).
Hit STORE again to finally store the preset.
You should see > Preset Stored < flash on the text display.
If you are working on a user preset and all you want to do is save what you had been working on overtop of what was there before, simply hit store three times.