If you want the hyphenation to be automatically applied while you are typing, Scribus can do it for you.
Go to File | Document Setup.
In the Hyphenator settings, select the Hyphenate Text Automatically During Typing checkbox.
Now draw a Text Frame (T) on a page.
Write some text inside it and you'll see that the text will be hyphenated if needed.
Some people like hyphenation in texts and some don't. If you like hyphenation, using automatic hyphenation will be very comfortable to work with. You won't have to think about it anymore. But you will reduce the control you have over text management. You can use the Hyphenation Suggestions box. In this case, if needed, Scribus will suggest you some hyphenations through a little window and let you decide. This window will appear for each suggestion, which we won't find very practical. Notice that even if you used automatic hyphenation, you can keep on adding your own hyphens if you don't agree...