Worms are a parasitic nuisance to your chickens and if left untreated will cause a problem throughout your flock and possibly yourselves. Regular worming treatment means dishing up worming pellets with their food. Best to follow the manufacturers instructions but generally this means giving enough pellets for a dose per chicken every day for 3 days once a month. Ours just goes in with their regular food but I know they like their worming pellets dished up in yogurt or porridge so if you feel kind you could give them a treat each month.
Remember worms are something to be dealt with all year round so plan a time each month and stick with it.