If you want to access the same files as other users in your lab, do not try to share a single local database. The best solution is to set up a shared SQL database that all users can connect to via their own local databases. See chapter 20 of the Geneious user manual for further details. The manual for your copy of Geneious can be found by going to Help→Online Resources→Download Manual.
You can also share files by using the Collaboration plugin, but this does require all users to be running Geneious at the same time for files to be accessible. You can also export documents from your database in .geneious format and place them on a shared drive for others to import into their own database.