Chinandega is in Nicaragua.
You can get to Chinandega from Managua on a mini bus or bus in Huembes Market. This costs $3 and takes 2.5 hours and is very safe.
Hitchiking is an option, as is renting a car.
Chinandega is past leon. Refer to ViaNica for more directions 
In Chinandega city you can either
There are school buses that leave from "El Mercadito" to go to other parts of Chinandega province, such as the town of El Viejo, where the rosquillas (cheese crackers) are famous.