I dont know how to do it on SkyDrive, but I can show you how to do it on Dropbox for free. sign up here: http://db.tt/YsLpfjwg
once you've signup and logged in, simply click the upload button to upload your file. after you've uploaded the file, to the right of the file you will a small icon that looks like a chain link. click on that and you can share the public link to the file.