Hello. I know, that I was being obnoxious, a long time ago. But now, I want to do better on IMCDb. So can anyone tell me, how to usually make and post an image for a vehicle for the site? Thank you. Even though, I tried before. But I had trouble with it.

Where did you had trouble? In which step do you encounter a problem? (to maybe explain that point instead of the whole process)

I was trying to post 5 cars on the Die Hard: With A Vengeance page. I made the pics by printscreen (what I do on IGCD). And for what I've tried, it seem to not work. So is there some kind of movie player on the computer I could download. And on posting the cars, I had trouble with using which ratio. Which is which? Thank You.

To make captures you can use Media Player Classic (MPC) or VLC, which have a capture function (in MPC it is in the File menu)
Depending on the source, resizing to correct ratio does not always have to be done: sometimes it is already good.
There was this topic previously explaining how to send pictures:
http://forum.imcdb.org/index.ks?page=forum_topic&id=1201&index=0
except the forum-post contribution thing, the rest is still applicable (image encoding, etc.)

Ironically I was looking for that topic earlier but couldn't find it.

I forgot the maximum height as I am pretty much always able to do it by width.