There are various ways to gain knowledge on software testing . I am a self made tester who moved from leading teams in a BPO to the IT industry and have about 6+ years of experience (This sentence is just to establish my credibility). I would suggest to read the book "Lessons learned in Software Testing" .I would consider this as a bible in software testing. In parallel pick a programming language ( Java or C#) and aim to get a mastery in that language. Also attend as many testing meetups/Conferences . This will help you to network and learn from others experiences. If you want to master testing , try the BBST courses . As i always say being a tester is not a career but a way of life.