RX8 getting hot
 

i have a 04 RX8 that has been getting hot. about a month ago it got hot so I changed out the thermostat and it seemed like everything was ok, until yesterday when it got hot again. I took a look inside the overflow jug and no coolant. Question, is there a full line on the tank when you are putting coolant in there, and what else should I look at. Also i can hear the electric fans kicking on. need some help on this one

what is this?

yesterday the car got hot again, it even turned off and wouldnt start until it was cooled off. now what