I have enabled ethernet sharing on my MacBook. Please help.

Is this bad or good.
? i live in a neiborhood, most people have locked wifi\
if i have ethernet on which means other computrs can connect to my internet, will that harm my mac? slow it down or virus or anything?
please help

If you have a wireless router it should be password protected and encrypted. You don't want to use open WiFi. Look at your router's instruction booklet, or go online and find the instructions for protecting your connection.