You need to checkin, online, right at the 24 hr mark....if your flight is leaving at 9am on Nov 12, you need to be online, ready to checkin at 8:58, Nov 11.
So....be all set to go, have all the names on the reservation checked off on that particular page. Then you can submit it. If it's too early, an error message will come up...just submit it again until it is accepted. Figuring out the actual time is tough.
So.....you submitted it, it went through. You will see something like this...
A23, A24, A25, etc. These are your boarding numbers. There are three sections...A, B, and C. The earlier you checkin, the higher (or lower depending on how you think) your boarding section/number will be. Those with medical issues will board first, regardless of their boarding assignment. Then, A1-15 will board, if there is anyone with those numbers...those are the business select people who have paid full price, refundable fares. There are seldom a lot of them.
When you get to the gate, you will see poles, with letters (A,B,C) on them. Then behind them, you will see smaller groupings...16-20, 21-25, 26-30, etc.
When the gate attendent gives the word, you will get up and stand in the spot indicated on your boarding pass....in your case it would be A23, 24, 25. When the A's are boarded, they make an announcement that anyone traveling with children under the age of 4 may now board (assuming they had B or C boarding passes). They don't have to wait for their particular number to come up. Once they are boarded, the B's board, then finally the C's.
Unless you have a large group, you should be able to find seats together if you are in the A group. I've never seen those boarding in the A group have to really split up...of course if there are more than 3 of you, you will have to sit in different rows, but those rows should be next to each other.
Even those boarding in the B group tend to find seats together if they head to the back of the plane. It is usually the C group that has to split up and scatter throughout the plane...and even then that doesn't happen a lot unless it's a larger group traveling together.
So...get online right before that 24 hr mark and get checked in. That should assure you that you are all seated together.
Flying can be scary if you aren't used to it. My advice? Just occupy your mind elsewhere. Bring a bunch of magazines, or an iPod, crossword puzzles, sudoku..whatever. Then, watch your flight attendents. If they are just going about their business, you're fine. Try to relax..flying really is a very safe mode of transportation.....this from someone who isn't the most happy person at 30,000 feet!! But, I've pretty much overcome my flying distress.