Have unsecured wireless line. Used to have WEP and secured bu somehow deleted a year ago. SLows streaming of net flix via tablet. HOw do I find or install an existing or new WEP?

FOllowing up on my last post - I have no encryption to keep others form off my wIFI. It's slowing my streaming of net flix through my tablet to the TV. How do I encrypt - WEP WPA??