How do I emancipate a slave ( رقبة), and what are the ways to achieve that?

Freeing slaves is a righteous and desirable act, and it may even be obligatory, but it has become difficult today. Therefore, whoever desires the reward of freeing a slave should say: "There is no god but Allah alone, He has no partner. To Him belongs sovereignty, and to Him belongs all praise, and He is over all things competent" one hundred times, for it is equivalent to freeing ten slaves. And whoever is obliged to free a slave but cannot find one, must fast for two consecutive months. But whoever finds a slave must free him, and should not resort to fasting except when a slave is not found.