As many people have said already, the actual embracing of Islam is a quick and simple process of reciting the 'Shahada'.

However, in order to fully understand the rights and responsibilities of Islam, I do strongly recommend that your fiance reads The Quran. THere are many English ( and other language ) translations around, and available online for free. Only once The Quran has been read, will one begin to understand what the religion actually means. Those of us who believe, accept The Quran as the final word of GOD, infallible and complete.

May you both be blessed.