how do you protect your wi fi from letting out siders use it?

One reason why I would never use it. All hard wired.

Also if you want the fastest data transfer then wireless is not the way to

go about it, especially if you have a crap internet speed to begin with.

These are few tips for keeping your network,away from those who would hijack it.

a.) Set up a password - or even better - an encryption key

b.) Turn on MAC address filtering and router firewalls

c.) Change your network’s SSID and make it invisible

d.) Assign IP addresses to your devices

e.) Avoid open, unprotected Wi-Fi networks,

Put encryption on the wireless router. The router's manual is the best source of info on how to set it up. That's why they exist.

you need to access your wireless router - probably by typing the I.P. address of the router into your browser bar. somewhere in the menu's that come up will be a "password enabled" setting. you'll need the original password though ... factory passwords are usually 0000

Set up encryption - WPA2 if all your devices support it, else WEP