Taking a bye is taking a round off from play. You can ask for 2 half point byes (3 in the 6-round championship sections), which means you get half a point for each round you're not playing. More byes is possible if you have valid reasons, but they will have to be 0 point byes.
If you want a bye for the first, or the first and the second round, you should not need to show up to ask for it of course, so we register such bye requests by email to either the email@example.com or firstname.lastname@example.org but preferably to both of us.
Byes after this must be requested at chess control on the site, before the round you want the bye for of course, but also at the latest before round 3 for round 3-5 (or before round 3-6 for Championship sections).