How to start using and developing on Ubuntu Linux?

Ubuntu Pocket Guide

If you're new to Linux, I'd suggest you look at the Ubuntu Pocket Guide. It goes through basic stuff that any user would want to know - window management, system configuration, etc, as well as some historical background on Linux and Ubuntu. You can skim through that and learn a bit.

Bash Basics

Towards the end, it also explains the basics of bash, which is the Linux command line. That part is interesting - you can do a lot more in bash than you can do in the Windows command line. For example, you may be familiar with this Windows idiom:

dir > directorylist.txt

...which means, "list the contents of this folder, and instead of showing the output, put it in this file."

In Linux, you can do that, and you can also do piping, where you direct the output of one command into another. For example:

ls | grep foo

means "list the contents of this folder, and search through the output for the regular expression foo." You can add as many pipes as you want and use a variety of commands.

You can also use brace expansion to run multiple commands in sequence. For example,

mkdir photos_{france,spain,italy}

will create directories called photos_france, photos_spain, and photos_italy.

If you're going to be developing in Linux, you should invest the time to read some tutorials on bash to take full advantage of it.