Hi! I need help, I dont know how animated an object

I want to know how I can animated some objects in my design, I want that they can move side to side in a simple way, I saw examples but i don’t know exactly how to do it .

In this link, you can see exactly what I am talking about! When you look the animated prototype you can see, the dog for example, it’s moving and I can’t find how can I do the same.

Thanks for you time!