To add properties, you must first be a registered user in the CMS. Jomres doesn't normally register users ( unless they've been added via taking a booking ) so use whichever mechanism the CMS offers to register your property.
For example, in the Joomla quickstart you have to allow users to register their own properties by first allowing user registration ( first option in the below image ).
When that's done, the Leohtian sidebar will have an option to Create An Accout :
Once you are registered, and assuming that site administrator has configured the system to allow registered users to add their own properties, you can go ahead and add your own properties.