Are you working from a laptop/desktop or an iPad ?
I believe there are differences in posting methods .
Any how , posting photos is discussed in this link.
Took me about three weeks to get on to posting, so don't give up .
A few things I've found ,
1. Resize photos , some formats will be over the forums posting limit . 640 pixels works for me .
2. When you have the attachment drop box open and have selected your photo , after clicking the download button WAIT until the box comes up saying " download complete. If you close the attachment box too soon the photo is lost in cyber space.
If you have your furnace info , make and model , please add that info to your post .