I would recommend starting from this tutorial on a new droplet, just to familiarize yourself. (https://www.digitalocean.com/community/articles/how-to-launch-your-site-on-a-new-ubuntu-12-04-server-with-lamp-sftp-and-dns)
Once you get the hang of it, you can return to your wordpress server and configure what you need.
Additionally, if you're interested in some helpful reading material, I would recommend check out this book: http://linuxcommand.org/tlcl.php
It's a really friendly introduction and is available online.
Additionally, I would recommend access your server from outside the console (the black box you are currently using). The console doesn't allow copy and paste. If you are on a mac, you can connect to your server with "Terminal"; if you are on a PC, you can access your server with "PuTTy" (http://www.chiark.greenend.org.uk/~sgtatham/putty/download.html). We have a tutorial on putty here: