I originally got the file from another thread here on this site, and the poster said something along the lines of "Just insert this into the Languages Sub Directory." But what exactly that really means I have no clue :(
Arena in English?

look in toolbar of Arena "Extras" dropdown you will find 'languages' and change into english.
But that is the problem--the only language listed in the dialog box is German. There is no English option, or any other option for that matter.

Mine works fine. Make sure "English.lng" is in the "languages" subdirectory, then start Arena. Once it is running, the menus will start in German. Select "Extras", then "Sprache Wählen" ("Choose Language"). You should be able to choose English there. Then it will ask you to restart Arena, and once it does, all should be in English. Good Luck!

Thanks, it works now.
Must just have been the location that I downloaded it from that caused the problem, because once I re-downloaded it from the official site then it had the "English" option on it.
My version is schizophrenic.
I have English selected under Extras->Select Language, but if I go into "Set up a position" and want to set the side to move I get a choice if "weiß" or "black". If I hover over the + sign with "LEV" beneath it on the task bar it tells me it's to "Stufe erhöhen", whereas if I hover over the adjacent – sign it tells me it's to "Decrease level". Everything else is similar.
Does anyone know an effective antipsychotic agent I can give it?
Can anybody help me get my Arena GUI running in English? I got the English.lng file, but I am not really sure where to stick it now that I have it :(
I am currently running xp.