Most likely you have been accumulating Steem Dollars and Steem Power, but you can convert it to STEEM the currency within SteemIt. From there, you can withdraw your STEEM from SteemIt to an exchange (there are many - kraken.com, poloniex.com) and trade it on the market for other cryptocurrencies. At the least, check out the exchanges to appreciate the breadth of the cryptoverse, and also look at www.coinmarketcap.com to see how many coins there are! Should you feel inclined to get into the market feel free to let me know and I can point you towards some great introductory posts and videos.