use the  FCKeditor

and there is a yellow square with a mountain looking like thing.

its right beside the smiley face almost

click on that

then enter the web address of the picture you already have online.

to get the address of the picture:

 right click on the picture

chose "properties"

and then a little window pops up that has a long address that reflects the location of the image

highlight that with your cursor (the address)

right click

chose "copy"

and then on the space  in the pop up from the lttle mountain picture

put your cursor in the address window

right click

chose "paste"

then click ok and it should show up