Body worship is a huge part of submission, where one person physically revers another person's body, or a specific area of their body. The submissive will be encouraged, with words or through punishment, to kiss and lick the part of the body that they are worshiping. However, worshiping can be done without encouragement from the dominant, as the submissive may just use their words and body to show how much they appreciate the beauty of the specific part.
There are a few different types of worship, but the most common are genital worship (penis or vagina), ass worship, and foot worship (which ties in to foot fetishes). While each area of worship and how to show appreciation of it may differ, it tends to be performed with either the submissive kneeling before their mistress or master to show they are lowly, or with them lying on their back and their mistress/master presenting them with the object they so adore. The dominant person in the relationship is still in control, as they can withdraw themselves from the affection at any time, should they feel it no longer pleases them.
Face sitting and smothering can tie in heavily with genital and ass worship, as the dominant can force the submissive to pleasure them and show appreciation via oral servitude. The submissive may also find this position gives them better access to the part they want to worship, so they can pleasure and please their master fully. It can also allow the submissive access to the ass if this is the area they adore most, allowing them to perform rimming.
Foot worship is usually done with the submissive on their knees before their mistress or master. The dominant may offer their foot to them, letting them kiss and lick at it. If the mistress is wearing stockings, they might instruct the submissive to remove them with their mouth before they can suck on their toes. While these are the main areas, body worship can be performed on any body part. Let your dom know which part you want to worship and beg them to allow you to do it.