1999 Dodge Caravan Meaning of diagnostic code

I have an issue come up where after driving my dodge caravan the transmission seems to slip in to a lower gear and will stay that way until I stop for a while, It will run great then after about 20 minutes it does it again. I had someone pull the diagnostic codes for me and I get codes P0700 which tells me Short or opened circuit in transaxel or failure of transaxel control module. The second code is P0731 which is ratio error in 1st gear, poor electrical connection, internal transmission fault. Can someone explain these codes to me in plain english that I can understand?