I think your magento installation has all the dependencies. That's why there is no dependency to install.
Try to install magento using setup wizard. Enter the following URL in the browser’s address or location bar:
http://<Magento host or IP>/<path to Magento root>/
I hope this will help.
To resolve this error, please open your php.ini file and set:
always_populate_raw_post_data = -1
For Windows, you can find the file in the xampp\php\php.ini-Folder (Windows) or in the etc-Folder (not /etc but etc, within the xampp-Folder).
Under Linux, most distributions put lampp under /opt/lampp, so the file can be found under /opt/lampp/etc/php.ini.