At about this time I direct my passenger into the airplane. The doors on these planes are pretty light weight and are easily damaged. They are not sturdy like a car or truck door. I took a guy up once and he broke my passenger door. I thought for sure it would be ok as he has been a pilot. So, I request that I do the door opening and closing. They are pretty simple with a little lever pulling a pin on the door post. Notice just forward of the door grab handle is a cigarette ashtray. There is also a cigarette lighter on the instrument panel but I don't allow smoking in my plane. Those ashtrays are noisy, being made out of metal, but I leave them there because it would be a mess to remove them.
There have been cases of doors popping open on takeoff. If it happens don't panic as you won't fall out or anything. Let me know and I'll close it as soon as it is convenient. It's no big deal.