We assume you will arrive by airplane. This means, you will come to the Okecie airport. From there you can take a bus, line 188. This first goes along the Zwirki i Wigury st., for about 6 kilometers. Then it turns right onto Wawelska St. Now, the bus approaches Riviera. The building is very characteristic, tall and in two shades of blue arranged into two large triangles. It is slightly to the right of the street. At some point the bus will go under Aleje Niepodleglosci, then it comes to the crossing with Warynskiego street. You should get off there, at a stop just before the crossing. Bus stops in Warsaw have their names. This one is "Metro Politechnika". The dormitory will be now vey close and clearly visible.
You need to buy bus tickets in a kiosk at the airport. You will need one for you and one for your luggage (unless it is very small). You activate the ticket by inserting it into a slot of a yellow device in the bus.
Youu can also take a taxi instead of all that. This is altogether less than 10 kilometers and should cost maybe 40 zlotys (10 EUR). Just avoid the taxi drivers approaching you in the airport hall - they will charge you more than a taxi taken at the taxi stand right outside the exit.
Here is the picture of RIWIERA