Before we go on to the first step, we need to keep in mind that to make an animated picture we need to have few pictures.
OK, Let's go on to the first step:
Open paint on your computer. If you have windows then you know what I'm taking about.
Resize the picture. Make sure you put the pixel numbers properly as your banner requires.
Write something or add other picture to it and make few copy of it. In my case I've made 3 copies.
Go to this site http://gifmaker.me/ and upload the pictures. After setting the speed click on Create GIF Animation button.
That's it, your animated banner is ready. You can see the banner below in action.