Start your search on the homepage, where you can search for round trips, one-ways, and multi-city train routes. Enter your "from" and "to" destinations using names of train stations or city names. For a train departing Berlin, you could enter "Berlin" to see all stations located there or search for "Berlin-Spindlersfeld Station."
If you have a rail membership card (e.g. BahnCard or RAILPLUS), select it from the dropdown. After entering in your details, click the "Search" button to see your flight options.
For all Deutsche Bahn tickets, you will be redirected to GetGoing's DB portal. All of your search details will automatically populate, and after you're done confirming your tickets, they will appear in your GetGoing trips page.