First of all, you should familiarize yourself with some of the basic technology of dubbing.
Once you've done this, build a portfolio with examples of your work; you can post these to a YouTube account etc. Companies will be reluctant to hire you if you have no examples of your previous work. This is difficult if you've never worked in the industry before, so you have to go out and make some yourself!
After you get this done, you'll need to do some research on the industry. Find the websites of the companies that do the work. Check out the dubbed stuff and try finding out who did it. Also, search trade publications like Variety or smaller ones that are specific to your language.
Once you get these, you'll have to begin the hardest part: getting in touch with the right people. You'll face a lot of "gatekeepers" whose jobs it is to prevent you from contacting the hiring managers directly. This will take a bit of luck and networking. Reach out to them on LinkedIn.com and industry-specific sites. Also post in your resume on the major job portals with your work videos.
Hope this helps.