SGxHeadshotz

Okay so no matter what pack it is, i've not downloaded anything I just installed the launcher, but when I go to to play a modpack, like i tried to load tekkit lite, it comes up unable to unzip file of some sort, I'm just wondering what I'm doing wrong, I have got a Minecraft account and have entered my details correctly, but I cannot load or play any modpacks. I'd be thankful if someone who's maybe had this problem or someone who knows how to sort it, would give me a guide on what to do, to get it up and running, Thanks.