This is a step by step guide that shows how to publish a text in the Roptsten testnet of Ethereum. In order to publish in the Mainnet you will need to select it in the first step of the following tutorial.
Blockchains are already used to store non-financial data for diverse purposes, e.g. to prove authorship of ideas or to prove the existence of a document. One of the largest files stored successfully into the Bitcoin blockchain is an image of Nelson Mandela.