knowing that different ways of explaining can help people to find their own best solution, I give you the explanation I gave in the German and Dutch fora.
There is an other explanation
here, pick the one that works for you!
Placing photos in the forum is not the easiest thing, especially if you want to link your picture to your photo page.
I'll try to clarify it here, with pictures
PHASE 1
click on post reply, then the window where you want to write opens
click on the blue rectangle

a small window opens. Write in the URL box http://www.panoramio.com/photos/small/xxxxxxx.jpg , where xxxxxxx is the photo number
click select

END PHASE 1
Now the photo is in the text box. you can leave it like that, but when you want a link to the photo page
PHASE 2
click on the photo, a small lightblue window opens.
click change

A small window opens
Write the URL where the link should lead to, usually http://www.panoramio.com/photo/xxxxxxx
Click OK

END PHASE 2
extra:
Photos will be placed in the middle. If you position the cursor before the photo you can click "align left" on the bar above the window.
If you want to put photos side by side, you first have to load all the photos and align them left.
place the cursor after the first photo, enter a few spaces, delete until the second photo jumps behind the first, cursor behind the second photo, etc.