The interface is dead simple. You go to the website and use the browse dialogue to select a file from your computer. JetBytes generates a random URL for your transaction. You then share the URL with the person you'd like to send the file to.
As long as you keep your browser open your friend can use that URL to download the file from you—once you navigate away from the JetBytes page even if the transfer is under way it will close the connection. When they load the URL they'll be given a save dialogue for the file you're transferring and from there the only limitation is the speed of your two connections. JetBytes does nothing more than route the file transfer through their web server, allowing you to share large files easily others even if one or both of you are behind restrictive firewalls.
There is no restriction on the size or type of the files. JetBytes is a free service and requires no registration or personal information.