Simply rub it onto the affected area of your garment and leave it for at least 20 minutes. By then, you should be able to brush off the remnants before you stick it in the wash for a deeper clean.
First, use some duct tape to seal the siphon jets under the toilet rim. Then, reach for some vinegar and pour a cup of it into your porcelain throne. Let it set for an hour or so before flushing, and don’t forget to remove the duct tape before relieving yourself.