Keep trying. Do you have the pictures uploaded to a publicly accessible gallery?
Here is how I generally do it.
1. Upload the file to Photobucket. Once uploaded, you should see it appear in your list of images uploaded. It will be the direct link path you want for the next steps.
Then when you create a post, hit the insert image button as noted by the red arrow below.
3. Once you press it, you will get a popup prompting you for the path to the image. Get the path from your Photobucket page like I highlighted above. Enter it and hit okay.
The image should show up as seen below.
This image's path is copied right from the Photobucket page. If you want to see, I pasted the path below as a link.
Hopefully that made sense.