For CPU, you should see a maximum of 70°C (before the fan starts). Under load with the fan on, the CPU temp shoukd range in the low 60. If you see higher temps than 70°C, then you should take out the main fan and remove any dust on the radiator.
GPU temp is the video temp. It can go over 80°C (assuming you have the 4200go).
HD temp is the Harddrive temp, depending on what HD you have, it can range from 45-55°C.

My GPU space shows as blank and i have a 4200 go ? Why would this not be showing up ?

NM, found it in options.