Trouble turning a bukkit server into tekkit via server host.

[Cheezy_mckeezy]

Hi! This is my first post on this board, though I've played tekkit for over a year. I'm hosting a server with Minecraft-illimity.com and I can't seem to make it bukkit. I have a tekkitcustomizer.jar file to put into the plugins folder, but I can't figure out how to actually insert it into the folder. Please help!