The Identify Inventory tab will only search for software components that are installed on at least 1 machine in your environment. If you are starting with a software release, then the process would go as follows.
1. Import software and create a new software release
2. At this point, do not create a software product - we will do that later
3. From the Deliverable Software view, deploy this software to the desired target
4. Allow software inventory to run and report this software has been installed.
5. In the Newly Discovered Software list, this software should now show up. Select it, and in the right hand pane, select 'Manage this software'.
Again, the key here is to deploy the software and then allow software inventory to run and report back that it is installed. Then, it can be easily managed just like the newly discovered software.