Go onto the page where you have your pics hosted.
e.g.
http://www.myflyfishing.estranky.cz/.../ryby/cound/20
Then right click on the picture and select 'properties'. Copy URL address.
e.g.
http://www.myflyfishing.estranky.cz/...inahled/20.jpg
Then when you're posting, click on the little picture button (looks like two mountains and a sun) under the 'redo' button and paste what you've copied in the little pop-up box and click ok.
Then bingo
Maybe you'd like to delete the other thread you've posted under pictures