If you do not have accommodation in Berlin, you can stay in the homes of private individuals or families. You can make a request for accommodation on www.helfendewaende.de even before you enter the country. Otherwise, go directly to the Ukraine Arrival Centre in Tegel.
Take the S-Bahn or U-Bahn to the station Jungfernheide. From there, shuttle bus number 410 will take you to the Ukraine Arrival Centre at the former Berlin-Tegel airport. This bus also stops at the U-Bahn station Jakob-Kaiser-Platz and at the General-Ganeval-Brücke. You cannot reach the airport by foot! The shuttle bus is free of charge and a bus comes every 10 minutes. The shuttle bus will also take you from the Ukraine Arrival Centre back to the Jungfernheide station.
Alternatively, you can take bus number 109 from the stations Zoo or Charlottenburg and transfer to the shuttle bus 410 at General-Ganeval-Brücke. Please note: You must pay the regular BVG fare to take bus 109.
There you will be temporarily accommodated and cared for. Afterwards, you will be moved on to accommodation in Berlin or in another German federal state. You will then receive your accommodation, social benefits and medical care at your destination.