The second link is dead.
The first one (although clearly incorrect, since it offers a 'delete option to people who go there) works via clicking on the 'Save' option.
This link might be better:
http://picosong.com/AL9e/
You'll almost certainly need this audio editing program:
http://www.audacityteam.org/download/
(Download the file and double-click on it to install the program).
After installing it, you'll also need to download this file and double-click on it to run it:
http://lame.buanzo.org/Lame_v3.99.3_for_Windows.exe
(For licensing reasons, the 'out of the box' version of Audacity can't save files in MP3 format. Running that second file fixes the problem).
However, while I've got a basic level of knowledge in using Audacity, I've been unable to make any great strides in reducing that hum. You might need to find someone who knows more about it that I do. Sorry!
I suggest posting a new question (so that it's more likely to get noticed), with a valid link to your sound file and asking for help with using Audacity.