Since linux is not an easy operating system to learn, you may need to attend some online classes or you can refer to some of the links like: www.linuxhomenetworking.com
, etc., there are so many like this. If you'll google you'll find there are lots of. If you're willing to pursue the RHCE then you'll get course materials. Thouroughly study them, get to know what is linux and how to install it, basic partitioning and configuration. Then you should learn the basic and then advanced commands, etc.. Go through some online books, they are available free of cost. You can also look for some videos also.
There are so many ways to learn linux, just search on google you'll get lots of there.