You do not mention what type of chrysanthemums you want to 'multiply' but you should find what you need here.

http://www.thegardenersalmanac.co.uk/Data/Chrysanthemum/Chrysanthemum.htm

I have to say it is a bit late in the season now, as the basal growth( if any) will have ripened somewhat so you may have to resort to semi- ripe cuttings, which usually take a bit longer to root.

If I saw a picture of the plant/ s you plan on taking cuttings from I might be able to advise you better....Tg