First Time Printer - Help with floating parts

[Cogliine]

Hello. I've just acquired an Ender 3 Pro printer which I'm super excited about and managed to print my first piece last night. I'm going to be printing a variety of Brio Wooden Train Compatible pieces to extend my children's collection. The first piece I've tried is here. https://www.thingiverse.com/thing:5186283 I've printed the non-Brim version. The issue I've had is that when it prints the two brackets at the top of the piece print poorly. I've attached the below picture. Each of these parts is free floating and not flat on the print bed. This is a necessity based on the piece. It also appears others have printed this many times with good effect. As stated I have zero experience but I'm confused about how this is supposed to work or what to do to improve it. Clearly, it's impossible to just put the filament in mid-air so how is this ever supposed to create a flat edge on that side? Again, I apologize for my inexperience Thanks