Page 18 of the rulebook. In other words, the first player (the one who lost initiative) has to place a plane. You can place one in a sector on the map, or you can place one on your land airbase. But, if you do that, then the rest of your planes that aren't rearming will also have to be placed at the land airbase.
So, you'll place your first plane, then I place my first plane, and we go back and forth until one of us places all that he would like to place for this turn. Then the other player can place the rest of his, and we go to the air defense phase.
I'll go ahead and put 3 Albacores over Schleswig 1/Blucher to save us some time. Now I've put 3 out and you put 1 out, so you'll place 3 aircraft next (unless you don't want to place that many, then just place all that you want that's up to 3).