This can be a bit tricky but cool when it works.
First of all you need to set up another blog or wiki that allows file hosting. Again I suggest you keep the username and passowrd the same to keep it simple.
I have used Edublogs
Make a post and upload the file you want.
Once uploaded click on it to open the web page it is on and link that to your blog.
How to create a delicious account
Click on the link above to see how the download will look. It is a good idea to make your file that everyone can read like a pdf or if that is too tricky maybe a WORD document that most computers can see.