In order to have URL for a file to download, you'll need to have online storage somewhere. There are a number of free services available, or you can pay to host your own site. Once the site is created or you obtain the online storage, you can use the site to store your file, which will have it's own URL. You should be able to find some information by doing a search for "Free online storage".

Another option....

How BIG is the jpeg file? If it's a relatively small file, (2-3 MB is max for this) you might open a free webmail account for just this purpose, such as Hotmail, (or maybe you already have something of this type) send the file to your own Hotmail account, then give the account name and password to the friend. (IF you feel secure about this individual) They can then download it from that location.

Hope this helps.