Lua interpreter

Ok I've looked and looked online for this and I can't find it.
I have the source code for the lua interpreter and I need to create it but I don't know how. I'm new to coding and I want to start with lua but I can't learn the language if I don't have the interpreter to try things on. So please if someone could give me like step by step instructions of how to do this that would be fantastic. Thanks.

Did you google for "Lua interpreter"? The answer is basically in the front page. Anyhow, assuming you're running on Windows, this should be helpful:
http://code.google.com/p/luaforwindows/

If that's not helpful, could you please be more precise about what isn't working or what isn't clear?

You don't really need the source code to learn Lua, in fact it would probably confuse you. As David says, it is available from the Lua site.

On this site is a copy of the Lua standalone executable:

http://www.gammon.com.au/downloads/dlmushclient.htm

(Near the bottom).

The exact link is:

http://www.gammon.com.au/files/mushclient/lua5.1_extras/lua5.1.zip

If you download MUSHclient (also from that first link above, or click the Downloads button at the top of this page), then Lua is built into MUSHclient.

I suggest reading the online book "Programming in Lua", which can be accessed here:

http://www.lua.org/pil/