Anto, all you have to do is
1 -- download the photographs from the camera to your PC
2 -- click the button below the posting box where it says "Attachments"
3 -- find the photo you want to upload in the dialogue box that appears
4 -- click "SAVE" or just hit RETURN.
Your Nikon probably takes huge photos (high number of pixels each way, low compression) by default, so you must either reduce the size of the photos on your computer (I find that 800 pixels on the longest dimension is good if saved at 90% quality) or set the camera to take smaller photographs suitable for sending up to the forum, which should be easy after you refer to the manual.
