How to set my gui?

[Tracubik]

Hi all!
I'm trying to make a simple program that essentially do this:

1) open a html file (extracted epub file)
2) search for occurrences like "ita-ly"
3) put them on a simple GUI: 1 text field and two buttons: keepy it and 
correct it (i.e. it will become italy)

now this is quite simple but how can i do it properly?
i suppose i've to first generate the window and than populate it, but 
where i've to put the "search for occurences" code? I don't think init() 
is the right place..

Thanks
MedeoTL