Capella is a 5 minute walk to the main road where buses stop every couple of minutes. The proce you pay depends on the quality of the bus. 60-80 pesos. They go straight to Santo Domingo, but they may make you change in Boca Chica. If they do that you do not have to pay any more, you just go onto another bus and the conductor hands over your fare. When you come back, get a taxi to 'Metro, Juan Dolio'. When you get on the bus - and it is a bit more expensive coming back - ask them to let you off at Metro Juan Dolio as well. There you can walk a few minutes to Capella or get a motoconcho taxi ( a motor bike). Do not pay the motorbike more than 30 RD$ each. They will try and rip you off!!!
Have fun
Matilda