Hi Wongchong adn welcome to GoY. You do not need to do anything for your broom it has flowered for the year and is now setting seed. This will not ripen for a couple of months yet - you'll know when it is ready as there will be a little sound and the black seed will fly off al over the place. Broom is a prolific self seeder so unless you want a lot of broom remove most of the seed pods.

As to pruning, cut back everything by half, but NOT to brown wood. Brooms soon grow very tall and 'leggy' if not kept pruned, but they will not shoot from brown wood only green.

thanks for your advice, I would like some other broom from the pods, would they just grow where they land or could I remove the pods and plant them myself?

Yes. Think I have already answered a question about this. Wait till the pods begin to split. Soak the little pea like seeds over night. Sow in ordinary compost and they usually germinate in Spring. You can keep some seeds back to sow in Spring if you like.