R+ and R- is the repeater offset. You program in the 442.9 (receive/RX) and then program in the 447.9 for the transmit. If you are using a scanner, just program in the receive frequency, but if you are using a transceiver, then you program in both. You might have a radio that does that for you automatically (ARS, which is Automatic Repeater Shift), my yaesu radios have that feature.
You can also get frequencies from Radio Reference, just look for an ARES/RACES section in your county frequency section.