If the photo is already on your iPad, it will be in the Photos section. In these forums, when you create a message, you have an option to attach a file; choose that.
Under the message area, a new button appears asking you to choose a file. Navigate to the Photos area and you should find the image! Select it, post it, and there you have it.
The cut/paste method doesn't work from iPad to another device.
PS: you might want to look at the Snapseed app for a really cool "Photoshop" type app to do cropping, color correction, etc. Tip: if you take a photo with your iPad, that picture is about 4x too big to post or email. Snapseed (or Photogene) will allow you to easily crop and size down to the desired 600 pixels wide.
See the photo posted above? Done with my iPad. It was cropped and the text was added with Photogene.
Review my info, see where I said the paste function does not work from iPad to other places?
COPY whatever image you want with your iPad.Actually the choice will be to SAVE IMAGE. That put it into your Photos section.
2. I suggested that you download Snapseed or Photogene* where you will make sure your photo is correctly sized: no more than 600 pixels wide and under 200k.
**Photogene allows choosing a new size with the EXPORT button. It takes a little exploring.)
3. When you ant to post it to thse forums, creata a message, then see yhe link under that message to ADD ATTACHMENT. You then use the CHOOSE FILE button to locate your photo in the Photos section. Choose the one you want, and post the message.
It really does work, it just isn't "cut and paste". You'll get it.