How do i secure my wireless linksys network?

my Linksys wireless network says "unsecured wireless network. I want mine to be secured.. Thanks to anyone who can ist.network" i want to make it secure. make a pword so we are the only ones able to access it. not use a pword everytime i jump on the computer, but just a pword so the 3 laptops in the house are the only ones able to use it.. Click by click please.. lol.. i did this in college and it was easy..