How do you use lua script in roblox

Open up a brand new script in build/studio mode. Copy/Paste your script or type one in.

The best place to learn to script Lua with Roblox is at http://wiki.roblox.com/index.php/Lua_Help this is where I learned to script.

Or use the Roblox Wiki. It is very helpful when it comes to scripting. My favorite article on it is 'The Absolute Beginners Guide to Scripting'. Hope this helps.