I'm not sure last time I tried to find episodes i got a bad virus on my computer, but i did find some safe places Disney Chanel has 2 episodes on their site right now i dunno if they will put up more or not. and I seen Itunes was giving the first episode out for free. you can also by all the episodes from there at about 3 dollars an episode.
Easy. Go to google and put gravity falls ep 1 and then one of the options will appear. When you want to search an episode of a cartoon or manga, always put the name of that cartoon and the episode. It always works. Interesting discovery, isnt it ;D???