If you want to advance your level of technology in Going Medieval, you will need to research.
But before you can unlock the ability to research, you must first build a research table. You can build a table via the production tab by hitting F2 and then selecting a basic research table.
After this, place it anywhere in your settlement to have a settler build it. Once built, you will unlock the research tab and can start researching more items such as farming and distills to make bear and wine. However, certain research trees will require certain books such as chronicles, textbooks, and thesis.
For example, the very first research you can unlock "architecture" will cost a total of 15 chronicles - you can also make these various kinds of books via the research table.
Just click on the icon marked below, and this will start a production queue for chronicle books. When a queue is started, make sure to increase the amount to have multiple chronicles made, you can do this by editing the number next amount.
You also may have noticed chronicles are only unlocked, don't worry this is as intended, and for other books, you must unlock better research tables.
That said, if you want your settlers to get on to crafting books faster, make sure to go to the job tab and increase the priority of research. You will also want your smartest villagers doing the research (the ones with high intelligence). You can also find out who these people are by hovering the cursor over the job research for each person.