Here are some quick query syntax examples:
Returns all of the blogs that have been bookmarked in Bookmarks and that contain the word red.
Returns any items containing the word red and that are tagged with the term colour.
Returns all of the activities that contain the word red that the user specified by the myuserid is involved in.
Returns all of the items that contains the word red and that the person specified by the myuserid and the person specified by the youruserid are both involved.