If the pictures are too big for the website, set the camera's resolution to its lowest setting and take some more. The lower resolution will make the images smaller and they should fit on this website. Check the pictures on your pc and find a couple that are clear and show the problem, and post them here. Make sure you turn the camera's resolution back up after you have taken the pics otherwise all your pictures will be small.
You should be able to adjust the resolution on mobile phones too.
If you are using a mobile phone to take pictures or a video, have the phone horizontal so the video takes up the entire screen. If you hold the phone vertical, you get video in the middle and black on either side.