Do you mean Cosmos plant Sue? Many are annuals, chocolate cosmos is a tender perennial. The annuals are easy to grow from seed if you have a sunny spot.

You can buy the seed at any good garden centre. Sow them in seed compost and they will germinate very easily. Pot on to larger pots when they have 4 leaves. Grow on til they are about 10-15 cms tall and plant out after hardening off for 4-5 days. Some grow 3 feet, others grow up to 6 feet tall! Read the packet carefully.
Lovely ferny leaves and very pretty daisy like flowers, the annuals can vary from white, pink and white striped, red. I am growing some myself this year, they will fill the gaps in the border. Keep well watered until established.Enjoy:)

I had a cosmsos last year. It was one of my favourites.