connecting to a remote oracle database using pro*C

Hi guys,
   I am having trouble with connecting to a remote oracle database using pro*c.
Currently my linux machine(say A) has pro*c installed and oracle installed. so im connecting with a string that looks something like this

   exec sql connect :username IDENTIFIED BY :password;

Now i have to shift my code to other linux system(say B). It has  pro*C and oracle installed.
BUT i dont want to use the oracle that is installed in this (B)system, but i want to use
the oracle installed in the other system(A). i guess i need to use a remote database connection string,

In the internet i found some connection string like,

EXEC SQL CONNECT :userid IDENTIFIED BY :password at :db_name using :db_string;

can you please tell me whether this would work and if yes tell me what the 'at' parameter and 'using' parameter is for ?

I am wondering where we have to give the machine name, database name, protocol to use to connect , port etc..etc..
the machine name on which im working is newdelhi.uta.edu and im trying to connect to the remote database in berlin.uta.edu, the database name in berlin.uta.edu is called 'webvigil'.

please give me a solution