The thing folds up into it's own envelope, and is very compact, and makes the job of the person reading thru the thing for the verification easier.
This is the dark corner of the radio / man cave where I work on these things.

ON the wall are my three options, either a #10 envelope, regular sized which i don't use often unless I am returning the stations own QSO report sheet, the #6.75 small envelope, and hanging next to them is the aerogram. NOW the aerogram is divided into three 4 inch sections, by the dotted lines on the other side. FOLD the top flap down and crease tightly. Feed this into your machine. This is the fold over flap and here is where you start your letter.
ON this flap is the inside address, the recipient's address, the date, and the QSL data, complete down to radio and antenna. QSL data consists of the date heard, frequency and meter band, where it was located if not obvious, and the SINPO code, followed by Radio - in my case Zenith Trans-Oceanic D7000Y. It is important with the Zenith to list the exact model because these things were made for over 50 years in both tube and transistor types. Next antenna -- 60" whip, or added wire?
When finished with this 4 inch section, crank it out of the machine, and then unfold the top flap, smooth out the crease, and then crank it back down into the machine. YOU now have space to write your reception report. A typewriter makes 6 lines to the inch, and Pica is about 50 characters to the line, and 'elite is about 65 in this size. Choice #1 - what size type to use. On this side with three four inch sections that makes for 72 lines (12 inches x 6 lines per inch) to fill in. It is time for a compact, "headline only" type of report.
This is an art you learn over the ages how to condense an hour or so program into a small space. Look at a newspaper and you will note that every story has some kind of headline. learn how to do it. ALSO remember - this is going to a foreign country, so keep your verbiage simple and follow the AP Chicago Style of writing rules. (Strunk and White -'The Elements of Style' ISBN 0 - 205 - 30902- X)
Be sure to tape your program so you can review the thing as you are writing the report, and do not have to try to remember everything or take it from your log / note book. GET names, especially the host of the program, and every person who is introduced on it. This solidifies you heard the program. At my age, it also helps in the review process of the program, it may take an hour to over two hours to finally get the whole thing down on paper.
When done with this side, take the thing out of the machine, and then turn it over and put in the return address in the upper left corner, and the recipient's address in the lower right. Be sure to mark it "AIRMAIL" -- I have several stamps to do this, then add the stamp.
When done, you fold the thing up, and close the two side flaps then seal them down, fold the top flap and seal.
The final looks like this -

Take it over to the post office and have one of the window clerks cancel it with the local stamp to do so. They will then stuff it into the tray and it is on it's way! Aerograms do not go thru postal machinery very well, because of their extreme light weight, being only a sheet of paper, so it needs to be hand canceled.
Wait about 8 weeks and you should get something back in the mail!
Enjoy ..
Sinifar