I strayed a little whilst locating the address since the directions provided on airbnb were slightly confusing and people directed me in different directions. If I am to indicate directions to this address I'd say exit the Roma termini station at the Marsala side. Cross the road and walk straight. You will come across the junction via marghera. Walk straight and at the next junction via versea turn left. The first block on the left with large green gate is your destination.
Otherwise, Francesco very diligently explained all aspects of the b&b and overview of the city. The room was clean and well maintained. The proximity of the place to Roma termini is a big plus.