Habe you read the help documentation? This explains how to upload images.

This image is 640 wide and is 211kbytes

I used Select image file to attach, the Browse button to locate it on my PC

Then I used the (img) button

That placed a marker in the post where the image goes (img/) I replaced the square brakets with round brakets as the image would have been uploaded twice.

Then press the Submit button

And hey presto it is posted with image where it is wanted.

You can only upload one image at a time with this method as explained in the help page.

This worked first time so there is no system problem.