Access simple search by clicking on the Music menu at the top of the page and selecting “Song Library“.
You can type searches into the search box that include words and phrases that appear anywhere in the description of a song. This includes the Title and Artist as well as all of the Albums and tag information including musical genre and dance styles.
Phrases are words that are grouped together using quotation marks (“). For instance, at the time of this writing, “My Love” will return 70 songs that have that exact phrase somewhere in the title or description while typing the same thing without the quotes will give you a list of the 2004 songs that contain either the word My or the word Love. You can also use the + (AND) symbol to include the songs that have both the word My and Love in them, but anywhere in the description rather than together in a phrase (My +Love returns 284 songs as of this writing).
This feature is implemented using the Azure Simple Query syntax, so you can get full details on the syntax (or how to make “simple search” not so simple) on their help page.
Some more information and examples are available on the blog post announcing this feature.