There are no limits on the Trial version for the main program, with the exception that we cannot activate the "in-app-purchase" modules. So it is fully functional, other than that.
You need to go to the "Charm Bar" (on the right hand side). Settings -> Setup -> Database and the edit whichever file you need (e.g. Clients, Projects, etc.).
Note you can download the full documentation from our website. Go to the Windows section and select Time Master. Scroll down to the very bottom for the PDF documentation.