First you have to get the bitcoin, unless you already have some. It is quite painstaking process but if you do your research it shouldn't take you more than few hours to get your first bitcoins.
Now for the exchange sites. I have completed many trades with poloniex and so far I haven't had a single problem. Poloniex is the largest burstcoin exchange site and over 75% of all burst is exchanged there. Another one is Bittrex with around 20% of burst exchanges.
Last option is to exchange with someone on forums. But beware of scammers and make sure you are trading with reputable user.
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