So you have decided to learn Linux..As you know Linux comes in different distributions, you might get confused while selecting the distribution.
The most popular distributions are given below.
If you want to install linux on your personal computer, you can go for Ubuntu. Lubuntu is the light version of Ubuntu. If you are planning to install linux on virtual box, you can go for Lubuntu since it needs less than 1 GB memory to run in a responsive manner.
You can download the iso (disc image file) from the official website and then install it on your machine as a standalone OS or on virtualbox or VMware Workstation.