Here's how to make an *.ico file in 30 seconds. No software to download...you need just a small picture. You can use *.gif, *.png and *.jpeg. Use this site: http://converticon.com/
to convert your picture to an *.ico file. If you want to change the icon on a folder (like I did on the video) I recommend you to check 32 x 32 in the export options and if you want to use it on your site (favicon) choose 16 x 16. Well I hope you like my 30 seconds tutorial! I made it for Forbes Teach Me Fast Contest!
EDIT: Sometimes there's a problem with the site and it can't save your icon. You can also use this site: http://iconverticons.com/
. It's very easy to use it. Good luck!