It is the slot in the front that feeds single sheets from the outside. It is labeled with a 1 on the center of the tray. The easy way to look at it is the tray you want is the same place you pull to put paper into the inside tray. Also, just to help if label help is needed we use the clear gloss labels from labelsbythesheet. The labels are not specifically called waterproof. Basically any vinyl / plastic label will be waterproof with a laser printer due to the nature of the printer burning toner instead of spraying liquid ink. HTH One more thing... The black toner is on sale at newegg.com right now for $64.99 with free 3 day shipping. http://www.newegg.com/Product/Product.aspx?Item=N82E16817401052&Tpk=hp%2b2600n%2btoner