Redid my macbook. How do I get my old iTunes library back?

[ratboy90]

I redid my macbook because it had gotten too slow. Works just fine now. But how do I get my old iTunes library back? I keep it on an external HDD but I don't know how to configure iTunes so that it reverts back to what it used to be. Thanks

 

[simsaladimbamba]

How to open an alternate iTunes Library file or create a new one