I'm using Imgur all the time - it's the only resource that works well for me. But I use it from PC - its smartphone app does something silly with uploading images.
Thing is, you don't want to make "Posts" in Imgur. Instead, in your profile you have to go to the "Images" page that looks like this:
If it's empty, you click "Add Images" and upload an image. Then you click on an added image and get the following screen:
You click on the blue button "Copy" beside the field labelled "BBCode (message boards and forums)" (the one that I highlighted with a red box) - it will copy a BBcode that you then simply paste into you forum post, and that's it.