Installing pg -v 0.17.1

I'm using/I want to use Postgresql as database, but when I type "bundle install" or "bundle update", I get this error, what do I do to fix this? :)

    Installing pg (0.17.1) with native extensions 
Gem::Installer::ExtensionBuildError: ERROR: Failed to build gem native extension.

        /usr/local/rvm/rubies/ruby-1.9.3-p392/bin/ruby extconf.rb 
checking for pg_config... no
No pg_config... trying anyway. If building fails, please try again with
 --with-pg-config=/path/to/pg_config
checking for libpq-fe.h... no
Can't find the 'libpq-fe.h header
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of
necessary libraries and/or headers.  Check the mkmf.log file for more
details.  You may need configuration options.

Provided configuration options:
    --with-opt-dir
    --without-opt-dir
    --with-opt-include
    --without-opt-include=${opt-dir}/include
    --with-opt-lib
    --without-opt-lib=${opt-dir}/lib
    --with-make-prog
    --without-make-prog
    --srcdir=.
    --curdir
    --ruby=/usr/local/rvm/rubies/ruby-1.9.3-p392/bin/ruby
    --with-pg
    --without-pg
    --with-pg-config
    --without-pg-config
    --with-pg_config
    --without-pg_config
    --with-pg-dir
    --without-pg-dir
    --with-pg-include
    --without-pg-include=${pg-dir}/include
    --with-pg-lib
    --without-pg-lib=${pg-dir}/lib


Gem files will remain installed in /Users/rsvmrk/.bundler/tmp/22196/gems/pg-0.17.1 for inspection.
Results logged to /Users/rsvmrk/.bundler/tmp/22196/gems/pg-0.17.1/ext/gem_make.out
An error occurred while installing pg (0.17.1), and Bundler cannot continue.
Make sure that `gem install pg -v '0.17.1'` succeeds before bundling.

Any suggestions?

Looks like you are missing pre-requisite libraries.

sudo apt-get install libpq-dev postgresql-devel

Then install pg

gem install pg