Create Registry and Read registry

Question

hello every one, i have created registry in windows when i m created setup. but i don't know how can i read this registry at my software's welcome form . or like main form . i want that when user click software icon on that time registry should be check if it is same values then software Should be open other wise will not open and give to exception to him .hope you understand what i want. its too urgent please help me tahnks in advance