Sharing folders works like this in Jottacloud:
First drag or copy the folder you want to share into the Jottacloudfolder (you can find this by opening filebrowsing on your computer).
You can initiate foldersharing by right clicking the Jottacloud program icon near the clock on your desktop and then selecting "Share a folder.." from the menu.
You will be taken to a webpage, this is the last step in sharing folders:
Type in the e-mailadress of the person you want to share the folder with. The e-mail adress needs to be the same e-mail adress that they use for their Jottacloud account. This also means you can only share folders with registered Jottacloud users. A free account can also share folders.
Type in a message for the person you are inviting, if you want to.
The recipient will now receive an e-mail where they can click a link to accept the invitation. When accepted, the shared folder will be created in their Jottacloudfolder, and the contents will start to download. Any changes made to the folder or contents by either parties will from this point be uploaded to the server, and then synchronized to all members of the shared folder.