I see people misusing this so I'll explain what "Place Inline" is for. When you upload a file by default they will attached at the end of each post, no further action is required to display the images.
The "Place Inline" button can be used to place BBcode in the middle of so you can display it where want:
We can then write some text after it. That is all the "Place Inline" is for, unless you want to place images in a specific place you can upload them and they'll appear at bottom of post like this: