As I understand you, 'highlight' means changing the background color. The Ctrl+K dialog shows the available colors. You can use 1 number, in which case it's just the foreground text color. If you follow it with a comma and a 2nd number which is the color for the background. If the final number is followed by text which itself begins with a number, you need to make sure that final number has 2 digits, in order to prevent the 1st numeric character of your text being used as part of the color number without being displayed.

The Ctrl+K character actually puts the $chr(3) character into the string, so you can use $chr(3) $+ 4,00text. The Ctrl+K character used by-itself is also the way to revert the text back to the default colors.

Note that when switching background colors, it's often easier to read if you have your text folllowed by at least 1 space having the same background color as the text itself, even if that means creating the visual appearance of having your text padded by a trailing space.