To catch a butterfly, you need to look for them during the warmer months and you need to know their favorite environments. Then, take a walk around your vegetable or flower garden and look on the flowers or low plants. Next, spray your hand with sugar water and then watch them land right on your hand. For more information, visit http://www.ehow.com/how_2085321_catch-a-butterfly.html.
To catch a butterfly you need a net. Then you just run after them and swing at them with the net trying to catch them. (I recommend swinging downward so you can cage them in and they can't escape when in the netting.)
never touch a butterfly on the wings, it ruins them and it could die. find a spot with bright flowers( they love yellow) and wait there. when u see one come, wait until it hits about two or three flowers so it feels safe. then, slowly stand up and quickly throw a net around it. if you want to have it as a pet, that's not possible, it doesnt work out well, they die in a week.