There are pictures and a video on the BowBiz website on how to put a topknot in. It is especially helpful if you want to put a bow in and have it actually stay for more than a few minutes. Here is the link:
How To Put In Dog Bows : Dog Bows, Quality Dog Bows - Yorkie, Maltese, Shih Tzu - by BowBiz
She sells little grooming bands but I always buy the latex free bands because they don't catch the little hairs as much as the rubber ones do. Amazon sells them in larger lots for less money. 500 for around $10.00.
Amazon.com: Latex Free Dog Grooming Bands by...
When you do it like the pictures and video show with two pieces of hair instead of one you can place your bow securely on the front section then use a band to hold the two pieces together and it holds the bow more securely.