Hi, I am in a similar position to for different circumstances, first you need to have a understanding of Linux including the command line (very important), than you will need to have a look around your local area to see if there are any courses at college, if it's like my area your going to have to learn on-line, there are a lot of free and cheap courses around some are useless some very good but can be a little confusing , but a good starting point, books try reading Unix System Administration Handbook read and understand your on your way.
Just Google the courses, do a lot of looking around, and decide what area you want to go into you you may like System Administration or Networking or something else , there are a lot of choices however what I have found is what I learn t is not always what I was trying to do in the real world.
I have tried to keep this brief so as not whittle on but the problem is when getting a qualification is finding a job, experience was a problem just like anything else then there's age they like to employ youngsters these days for there own reasons. Also some company’s would employ Microsoft qualified people others would want both Linux and Microsoft and other just Linux.
I would try to stay with company’s such as Red Hat and Ubuntu and well know on line learning colleagues, in the none commercial world in the UK not many people even know of Linux and those that do can fix most of there problems themselves or get advice on forums and put two and two together. The Internet is your friend here and you will find a lot of the courses are from the USA.