Take a clean cup and add 1/2 tsp of water and then 1/2 tsp Epsom salts to it. Stir the contents of the cups until all or most of the salt you added is dissolved. Do not use clod water because mixing Epsom salts in cold water for would take a longer period of time.
Add 1 tbsp white glue to another cup. Make sure that the glue is uniform and does not contain and lumps. Stir if required.
Pour the Epsom salts mixture into the cup containing white glue. Use a craft stick to mix the contents of the cup until the white glue and salt water cannot be differentiated from each other. As the white glue mixes with the Epsom salts mixture, you will see Silly Putty forming. It would complete when both ingredients are properly mixed.
If you want to make Silly Putty in a larger quantity, increase the ingredients used proportionally. For instance, for 10 tbsp white glue, you will need to prepare a mixture of 5 tsp Epsom salts. That being said, if it is the first time you will be making Silly Putty at home, it would best to make a small quantity first and check the results.