You need to use a bibliographic database. LibO includes one, but it needs some work to get it working (you need to fill the database, create and set a bibliographic index, format the fields…). I describe the whole process in detail in my book, but if you don’t want to mess with this tool you can also “cheat” a bit to get a similar result by using a numbered list and cross-references. Here it’s the process. At the end of the document insert a numbered list with the target text; now in the point you need the reference go to Insert → Field → More Fields → Cross Reference tab and select Numbered Paragraphs, where you’ll find the list of all your items: on the bottom-left you can pick what you need (the number, the text, the page…).
Another popular option to build a bibliography is to use Zotero, but that need some learning too.
EDIT: check this sample file for the “numbered list + cross-reference” trick:
EDIT 2: a screenshot