Copying text from a source, then converting to XML

I have a question about this. Some of the question may not pertain to 
XML, but if anyone knows a method, that'd be great.

So, I basically want to automatically search a large number of documents 
for certain keywords. When I find that keyword, I want the paragraph the 
keyword is in, not the page, to be copied and pasted somewhere. After 
that, I want to convert the pasted text to XML.

Does anyone know a method for doing either of these tasks? Copying 
certain paragraphs or substrings of text that have certain phrases in 
them, then converting to XML? Perhaps there is a script of some sort? Or 
a free program?

Any help would be appreciated.