How to download a torrent remotely

First of all you need a simple torrent client running in a Linux machine.
For the propose of this tutorial we are gonna use Transmission.

To install Transmission:
apt-get install transmission-daemon

after installation, Transmission is running on port 9091. To access to Interface, type on the browser your IP address and Transmission port: 192.168.*.*:9091

You might need to configure user and password. Configuration parameters are in file: /etc/transmission-daemon/settings.json.
Please stop the application before changing any config values: /etc/init.d/transmission-daemon stop and start it again after you are done: /etc/init.d/transmission-daemon start

To achieve worldwide access for your machine we are gonna use a free service called no-ip. Free account can be created here: https://www.noip.com/sign-up

To install and configure noip in your computer, download the tar file to the directory, from no-ip.com with: wget http://www.no-ip.com/client/linux/noip-duc-linux.tar.gz

Unzip the files and once in the unziped folder, make the program with make and then make install
After complete installation, login to no-ip.com to confirm the client carried out it's first update.

Last and most important step is to configure the port-forwarding in your router. The basic idea is that you type something like this in the browser username.no-ip.biz:9091 and you can access to your torrent application from anywhere.
As every router is different, have a look here if you need support in this configuration: http://portforward.com/english/routers/port_forwarding/routerindex.htm