All you need are the betting addresses. Send an amount to an address and wait for a return transaction. The only problem for you is knowing the betting addresses since you can't get on the site. One way of finding them is to look in the most popular address section of blockchain.info, https://blockchain.info/popular-addresses
, most of the addresses are there (note that there are similar services like betcoin but there is doubt whether or not they are trustworthy).
I suggest you look up the addresses yourself so you don't have to trust me but here are the addresses I have for sdice:
win chance / address