Just google " free hosting " and it will come up with some hosting sites that will let you upload the file.( that is found under SI/FM13/Games. Try use one of the hosting sites that don't require you to register to download a file though ( registration might be needed for the upload though)
find the save game in Documents, Sports Interactive, Football Manager 2013, games
then put it in a zip file or a rar file so it's a smaller file size then you should be able to upload it to somewhere like mediafire. Not sure exactly where will work as they all have different file size limits, which I don't know and depending on how far through the save you are and how many leagues and players are loaded then the file size of your save could vary quite abit.