Oracle Database Discussions

I'm a total beginner, and am trying to access a .Dmp database. I have installed (on Linux i386):

Instant Client Basic 11.2 + SDK + SQLPlus

I'm aware that I have to further set the environment variables ORACLE_HOME and LD_LIBRARY_PATH, and think I know how it should be done.

The files installed in the oracle directory are as follows:
$ ls /usr/lib/oracle/11.2/client/lib
glogin.sql libocci.so libsqlplusic.so ottclasses.zip
libclntsh.so libocci.so.11.1 libsqlplus.so xstreams.jar
libclntsh.so.11.1 libociei.so ojdbc5.jar
libnnz11.so libocijdbc11.so ojdbc6.jar
$ ls /usr/lib/oracle/11.2/client/bin
adrci genezi sqlplus

But this is where I hit the wall. Just a couple of questions:

How do I make the Client to access the data? I've read a bit about name resolution such as tnsnames.ora and EZConnect, but have no idea what these are, even conceptually.

How do I actually start/configure the Oracle client? Is there an executable somewhere?

Can the .dmp file be even read by the client or do I have to use the SQLPlus to make queries (as I've read somewhere)?

As you see I'm clueless. What are the next steps, or could you point me to a practical tutorial that would show what I need to do.

Thanks a lot for any help..