Hi Nila,
You should be able to get your FTP working using the lib curl. The sample use of libcurl for HTTP Get request is already available in the HTTPGET sample.
Following the HTTP Get sample you should be able to build the FTP client code using curl. Below is FTPGET c example code using curl which should provide you the quick reference to get started:
https://curl.haxx.se/libcurl/c/ftpget.html
Below is a command line example if you wish to give a quick try over the command line:
http://linux.byexamples.com/archives/320/using-curl-to-access-ftp-server/
Once your application is downloaded in the target over FTP, you can use the update tool in the target to install the application.
Thanks
Pankaj