Read/write variables which are not in DBs using S7.Net library

Question

I'm currently programming an app in C#, I have to make a connection with a PLC through TIA Portal. I'm using S7.Net library which allows the connection and the data exchange.

However, every videos I've watched read and write variables from DBs :

ushort val = 40000;
plc.Write("DB1.DBW0", val);

but I'm not using DBs, only PLC tags and this doesn't work :

bool val = true;
plc.Write("I0.0", val);

I don't really know if it is possible, or if it exists another library allowing it.