To ground yourself, either touch the PC case metal frame/side panel when PC is plugged into the mains OR when you need to ground yourself while working with PC, touch the metal side of any big household appliance, e.g fridge, washing machine. If you have central heating, you can also touch the metal radiator or pipes for same effect. You can also touch the metal water pipes if you don't have central heating.
Note: avoid putting PC on the carpet since carpets can generate static electricity. Also, avoid wearing any polyester clothes for same reason. Cotton clothes are best since those create the least amount of static from all clothing materials when you wear them.