It is really easy. Just copy an image from a website (usually right clicking with your mouse on a picture will give you a 'copy image' option). After that, just paste it in this box (right click and choose paste). You can also click on the picture frame icon (see below), to add it using an actual link. Make sure you have permission to use whatever image you include.
You can adjust the width so it fits properly. Just change the numbers as needed after double clicking on the image to edit it.
We don't currently have the ability to add videos yet. However, you can submit video to us on the KidzTube section if you wanted.
Registering for a KidzTalk account will allow you favorite/follow other accounts, or save specific questions so you can find them later. It also allows you to vote on questions/answers, which is important. Finally, it saves you the trouble of having to enter an email address each time you want to be notified that your question or answer was replied to by another user. Another benefit is that you don't need to complete the verification challenge question whenever you ask/answer a question.