Getting in Siena:
The closest airport from Siena is in Florence (Aeroporto di Firenze-Peretola) and it will only take about 30 minutes to reach the center of Florence.
The next closest airport is in Pisa, and it will take you about 2 hours to arrive in the main train station in Florence.
From Florence to Siena you could take
a train (arriving at the train station of Siena where you would need a taxi or bus to go to the center)
a bus (arriving in the center of the city of Siena).
Accommodations are NOT included in the course fee.
The course is held in the center of Siena which provides several option for the accommodation (AirBnB, hotels, hostels...) at a affordable price. Here is a list of possible accomodations.
Note that the center of the city is inside the walls and it takes between 20 and 30 minutes to go from the different gates of the city. The university if close to the gate "Porta Romana".