How did you transfer it to your applications folder? Did you just transfer the file you downloaded? If that's the case that's where you've gone wrong. Double click on the dmg file you downloaded and you'll get a dialogue box that tells you to drag the Skype icon to the right and drop it on the Applications icon. Do that and that will install the programme in the applications folder. Then, when you click on that, Skype will open and you'll be able to chat to your hearts' content - I hope! 
