you can't post an image from your pc, unless you are running a web server on it and have an static IP address.
You either have to upload it to a website that allows remote loading or attach the file, in that case, you only click on browse, pick the file and then it's uploaded to the server and others can see it by clicking on the link.
I can upload pics from my PC very easily. All my pics are stored in a file in the 'my programs' directory of my hard disk.
To post a pic, I just click on attach file when I'm replying to a post and then select whichever pic I want and press return. Then click 'submit reply'.
If you cant do it that way, then I haven't got a clue .
Example: Click on the link below to see a great pic.