How do you protect your eyes from harmful radiation when working on computer?

There is no harmful radiation from the computer. Your eyes can get tired on the computer for a number of reasons. You may have refractive errror and need glasses. You are likely not blinking enough while working and the eye may be drying out. You may be not taking enough breaks. You chair/desk/monitor/keyboard set up may not be ideal and causing back or neck problems that are manifesting in the eye. See an eye doctor to check for refractive error and dry eye. You may need to use artificial tears two or three times a day. Look up from the computer frequently, take a 30-60 second "stand up and stretch" break every 20 minutes, try to break up your computer work with other non computer work. If your employer has an ergonomics person, have your workplace set up analysed. See the link below for other computer use tips.

hi friend we should blink our eyes as many times as possible

Most computer screed that use a CRT now have a "Screen" built into the front glass. LCD screens do not project a stream of electrons. There is no radiation from them. In either case there is plenty of eye strain as a result of prolonged use. There are screens that you can clip over the front of the screen

Never heard of this. Hmmm..... I have an LCD screen, also.