If you plan on freezing your yeast you need to prepare it with glycol to keep the cells from rupturing when it freezes. Not the easiest to do. Just stick your tupperwear container in the fridge. Then make a starter when you want to use it.
In the future you might want to use glass canning jars with gasket lids instead. Those can be boiled to steralize, and can store your yeast just like folks store pickles.
If you do a searh you will find the yeast washing sticky as well as stickies and threads about freezing and other ways to store your yeast. There's quite a few threads on it, and many are the stickies in the yeast section.....that's why we have a yeast section, to have info about stuff like that.