First things first, improve your grasp of the English language. Next, join the Custom Electronic Design and Installation Association (CEDIA- www.cedia.org
), and take advantage of their classes throughout the year (some will be in your area). Another resource is equipment manufacturer trainings at local AV distributors. They are usually free.
You can purchase video recordings of installation methods. One provider is The Training Department (Google for their site). There is no replacement for hands-on experience, however. Get a job with a local company conducting custom installations, start at the bottom, then work your way up. Most companies provide training on and off the job. Some are members of CEDIA and may even pay for your classes. Your aptitude, work ethic, enthusiasm, discipline, communication skills, and desire will determine how far you can go in this, or any, industry.