Here are seven basic story plots that will help you with your writing. I will use my character, Ted, to demonstrate how to build a story up. Ted is from 'The Teddy Bear Scare' and he didn't want to be cute and cuddly like all the other teddy bears.
The Quest : This is perfect for Ted as this is the plot I used for his story. Ted wanted to be scary so he set out to find ways to become a scary bear. He gets what he wanted but at what cost?
Comedy : It is hard to know what children will laugh at - but they do laugh a lot! In a comedy plot Ted might fall over, get his words mixed up, pick his nose, scratch his furry bottom or make a rude noise. Children will laugh at these.
Rags To Riches : Ted may be poor and scruffy but what if his Teddy Godmother told him he was really Prince Teddy the Third? What if an evil Jack In The Box had taken over Prince Teddy's palace and cast Ted out when he was a baby bear? Ted will have to fight to get his palace back.
Tragedy : Ted could lose something or someone important. Perhaps his best friend is given away in a charity bag. Ted must find his friend, no matter what.
Voyage and Return : Perhaps Ted was put into a charity bag by mistake. He undergoes many owners, not all kind ones, until he finds his way back home.
Rebirth : Imagine Ted as King of the Toybox. He's selfish and unkind. What happens to make him change his ways?
Overcoming The Monster : This is a great one! There could be all sorts of monsters that try to get rid of Ted from the playroom. They could become his friend but then trick him in some way so that his owner no longer likes him - Ted would have to clear his name. The 'monster' could be a cute kitten toy and only Ted sees how evil she is.
These plots should get you started on some story ideas. Think of the most ridiculous ideas - they are usually the fun ones!