PLEASE help me out! This is killing me!

i have buttons in my library. I try to put the code

getURL("http://www.blahblah.com", "_blank");

into it when i edit it from the library but it always says “current selections can’t have actions applied to it”. How do i get to it so i can have a link pop up when i click the button? does the “getURL” also work for files on my computer? for instance i want to click a button and have a movie pop up from one of my folders on the c drive. what would i code to do that? thanks SOOOOOO much to whoever can help me out, i have been trying to do this for days…