i am new to Libre Office and formally used Microsoft Office and it had a place to create labels or envelopes easily.
Using Writer, choose the Insert menu item and then Envelope.
For labels see:
https://help.libreoffice.org/Common/Creating_and_Printing_Labels_and_Business_Cards
http://templates.libreoffice.org/template-center?getCategories=Labels&getCompatibility=any
How do I create an envelope?