Hi team, I'm trying to use the Direct connection, but can't find description about filed Instance Name and Protocol, what for they are used?
If you don’t know what they are, you probably don’t need them. Click where it says “less” and they will go away. 
Instance name is generally only needed when you are connecting to a RAC database and want to specify a particular instance of the cluster to connect to.
Leave protocol on TCP unless you are connecting to the SSL port on the server.