Use Speccy, as x BlueRobot mentioned, fill in your system specs so we know what components you have, this is the only way we can help.
Start your computer, don't open anything, this is how you get your system at an idle.
The lower half of the RealTemp window has a 'Minimum' and 'Maximum' area, these will be the idle and load temps.
Your CPU core idle temps look ok, 33-37°C.
Your CPU is a 3570K Intel, from the FSB 103.02MHz I would guess you have a Gigabyte motherboard. Intel® Core™ i5-3570K Processor
This is your CPU data sheet.
Tcase is 67.4°C
Add 5°C to get the max CPU core temps 72.4°C, this is the limit, if you see Realtemp reach this temp, you need to close all programs, the temp should go down. If it doesn't then shutdown your computer.
When you fill in your system specs we can make further suggestions.