Becoming self-employed - tax?

by Eddie
(Sweden)

I am thinking of moving to Bolivia and supporting myself by working as a freelance translator through the internet. The company I am currently working with in Sweden (where I live now) is more than happy to work with me in this way. My question is, then: what rules exist in Bolivia for this kind of work? Do I have to register as a business or is there a simpler way? I know it would be very easy to just let the money turn up in my bank and not tell anyone about it, but this has to be completely legal. So what should I do and how much tax can I expect to pay on my income?