I've just copied the site's instructions and it's no wonder that people have trouble.  here's my way....

Set up a folder on your HD labelled OGFBpics.  Find the pic you want to post, open it in an image manipulation prog like Pshop and adjust cropping, contrast and brightness.  Once you have this right adjust the image size.  What you are after is a JPEG at 72dpi and a maximum dimension of 6 or 7 inches.  This will be about 450 to 600kb, and will appear the right size on the page.  Save this version in your new folder (OGFBpics).  Go to submit picture and enter all the information.  Hit browse and find the OGFB file, highlight the pic you want and it will automatically enter into the box.  Hit submit and as soon as the URL appears copy it.  Go to the topic where you want to post the pic and use the submit pic box on the menu.  If you do nothing it will be on the site but not in the topic.

Hear all, See all, Say nowt.

Ate all, Sup all, Pay nowt.

An if ever tha does anythin for nowt, mek sure tha does it for tha sen.

Reducing the size to a few inches and reducing the resolution to 72dpi is a great way to present photos on a website, but the disadvantage is that anyone who wants to download and print it out in the future (and you may not want anyone to do this!) will find the overall quality very poor (loss of tonal definition etc).

An alternative would be to make the resolution 300dpi (in Photoshop or similar) but change the PIXELS to 650 on the longest edge of your image.

This way the image retains its tonal quality (300dpi vs. 72dpi) yet becomes a small enough filesize to upload efficiently. At least, this is the convention which was recommended to me by professional website designers and which I now follow whenever I upload stuff to OGFB.

Reducing the pixel dimensions to 650 also helps to keep the screen width narrow so that if a large image is published, you don't have to scroll from side to side when reading the topic's text.

On the subject of people having difficulty publishing their photos (I think both PC and Mac users have this problem in some cases):

I discovered that in order to get the URL which the system needs to publish the pics, I have to use the FireFox browser. However, this doesn't then let me add comments, so I copy the URL, switch to Safari (being a Mac user; I guess IE would be most used by PC users) and post the comments there.

If the OGFB server is having a particularly pernickety day, I upload my photos to a separate server (in my case, the Apple Mac one) and grab the URL from there. The disadvantage is that the pics don't reside on the OGFB server and therefore may not always show up due to some systems' firewalls etc, but the advantage is that if the OGFB site goes kaput (as it has done a couple of times due to hacker activity) the images aren't lost forever.

I hope this information is useful.