Welcome to Android Forums.
Ok, from what I see, the LG 855 is also known as the Marquee, right? If so, here's the section at AF dedicated to that phone.
There you'll find it's "All Thing Root" area, where the good folks that know it best should be able to help you get it rooted.
Best of luck, and if there's anything else we can help you with, please don't hesitate to ask.