how do I include an external header file to unreal?

[Lehis]

Hello , I'm creating a launcher for my game.. and now.. when the user singup in the launcher.. it temporally saves the

<Email>HELLO@hotmail.com</Email>

and

<Password>pass123<Password>

in an Xml file... I can acces to that file using standar C++ codes... but how can I add that code into unreal ?? please help..