Official Ubuntu Documentation
Ubuntu has nice docs. I suggest you look through them if you need any info.
For more in depth info take a look at rute and tldp
The Linux Documentation Project
For learning Command Line I suggest:
LinuxCommand.org: Learn the Linux command line. Write shell scripts.
After that you can find pretty much any answer using Google.
What I did when I was first starting out was to make a webpage with all the info I found helpful that way it was all in one place and i could access it from anywhere.
How to Learn Linux, Using Linux