entry points security

Just bought a computer friend let I to install a entry points in computer security that can protect your computer and will avoid some virus into his computer? Listen to the friend of the things I said I will give my computer installed at night entry points for security, friends listen to what I said after I bought the new computer will often do check for my computer, that computer will be used for a long time, listen to the friend I know the things I say, this computer now I will take care of me, friends heard so speak to me and said she is now with the computers are used a lot is because often do check will be used for a long time?