How can I create a new key in dictionary with blocks

Hi all,
I am new to kodular and wanted a little help from you guys. I am making an app where i can show info about different countries with Firebase DB. I am storing the values from firebase to dictionary and want to create a new key whenever data is added to firebase. But there is no option in dictionary blocks where i can create a new key in an existing dictionary. Please help!

Thanks in advance​:blush: