MultiChain is not a smart contracting platform – to understand the rationale behind that decision, please read the "What about smart contracts?" section of this blog post:
http://www.multichain.com/blog/2016/09/introducing-multichain-streams/ – and several other blog posts going into the subject in more depth.
Perhaps you could tell us what you would like this smart contract to do, then we can tell you if there's an alternative way of doing it with MultiChain permission, assets and/or streams.