In a small town like this, much better to walk than trying to move the car, especially as most parking is towards the outside of the centre. There are some steep streets , so be warned !!!
The Tourist Office is in the corner of the main square and has a fair amount of maps and stuff, even in French and English. Very friendly and competent staff. But the major attraction in the T.O. cannot be seen from the outside, but knowing it is there, you can ask the staff to have a look at the inner courtyard and outside balcony of the "Manor of the Counts of Ribadavia". This baroque house dating from the 17th c. started being used when they abandoned the adjoining castle, falling into ruin.
A walking tour of Ribadavia should start from here, where you can pick up a map at the Tourist Office in the corner of the square.
Always have eyes in the back of your head to spot the unusual, or through a gate : i.e. off the beaten path.