When you post a comment there is a button at the bottom called "More Options", click that button.
Underneath the window you type stuff in is another button called "Upload a File". Use that to add an image for us to view.
When you take pictures of the fish, plants or tank, set the camera's resolution to about 2MB or as low as it will go (some only go to 4 or 6 MB). The lower resolution will make the image smaller so there is more chance of it fitting on the website.
If the image is still too big you will have to put it on an image hosting website and copy the link/ address to here. Then we can use that link to view the image at the other website.
Make sure you use a camera flash and have the room & tank lights on, and curtains open (if it is day time). The more light the better the image will be.