Oracle 11g connectivity over windows based client-server net
Assuming that these machines are sitting in the same network domain, have no firewalls between them and that you're running with everything "as standard", then you should be able to access the Database Instance running on PC1 from PC2 using these parameters in SQL Developer: 

Connection Type: Basic
Hostname:        PC1
Port:            1521 
SID:             SID of database instance (ORACLE_SID from PC1)


For connecting your Application, check out https://www.connectionstrings.com/

If you're getting Oracle (ORA-?????) errors, add them into the question so we can [try to] diagnose the problem.