@Mes 

Hey Mes, we would need more details in order to help. Typically, first you need to install the Kasa Smart app on your smart phone (iOS or Android).  Once installed you will need to connect to the default network for the smart plug (1 at a time) then choose that device and follow the on screen instructions.  That should be it but if you did that and have issues please give us a detailed account of what happens and any errors you recieve.