[Koha] How to print custom slips from Koha

Hi all I have installed Koha Koha 3.20.x on Ubuntu and have created a custom slip using Koha>Tools>Notices & Slips for a library (only for print). Now I dont know how to make this slip to print at the time of checkout automatically or manually. sorry i could not find help in manual. any help plz.. thanks Sana Afzaal