First of, this topic belongs in Publishing rather than in MOCs. So don't be surprised if your post and this thread suddenly isn't there anymore where you expected it to be. :-)
Regarding your pictures there’s something else you should do:
Resize your pictures!
When I clicked on the link to your picture my screen was filled with red bricks, bricks from the wall of your house, not Lego bricks. That’s not good. The screen should be filled with the image of the Lego only. Here is what you should do:
I don’t know what kind of picture editing programm you have got on your machine, but in general in the menu bar you'll find something like "edit" or "picture". Click on it and you find something like "resize...". Resize to 800×600 pixels, at the most to 1024×768 pixels. Don't worry, that's still big enough to see all the details, if the photo is clear. If the photo is not clear: Go and take another one.
After you resized your pic click "file" and "save as...". Now you Save the pic under a new name (something that tells what is the pic about, "castle01" for example) as a *.jpg file. While doing this you are probably asked to choose the compression ratio. Choose 80%.
Now you got a picture that is worthy to be uploaded to BrickShelf.
This is just the sort of nonsense up with which I will not put.