Doubt on Always-on ApplicationIntend-ReadOnly and ApplicationIntend=ReadWrite

I Have Deployed Always-on, and I have routed read query into secondary server, but my question is that, how can I make connection string on application side which will divert. Insert, Update and Delete to Primary server and Select query to Secondary server. Do I need to create two connection string? or one connection will be okay.......... I am in confusion any insight will be highly appreciated.