Multilingue Site - Custumer needs to manage its content

Hi dudes.
I was thinking about this site I'm working on.

It's an asp.net with VB project, where we have 3 idioms on it.

I believe that using strings and/or resources like txt/files, I can do the runtime language changing easily. But, at this time, I could not find any source that shows it clearly enough so I can implement it on the project. Tips from this community are welcome then.

As I made the entire site using Link and Labels components, using there resources won't be hard.

But, my main doubt is: How can I make this in a way that my custumer has control of the strings/txt files, changing it when he needs, not depending on me to? Plus, I have an option to use SQL/Database. My fear at this last option is that the strings get a little weird because of bad formating/ascii code, etc.

That's it.
Thanks in advanced.

BTW, sorry my weird english, as it's not my main language.