First step is to install the Quests extension.
Then you need to navigate to the Quests section on the left and start setting things up how you like it.
You add a quest under the Quests tab and select “New Quest” where you enter the name, description, xp and the completion code. The completion code is what players will enter to complete a quest. You can reveal these codes to players in various ways. I have one on my welcome page, and some that I give them in chat, but most of mine are on signs hidden around my servers.
Players have to type the command /code followed by your code word in order to complete the quest.
When you have several quests in your Quest list, you can order them or nest them if you like. You simply click and drag them around. For a nested quest, the players must first complete the outermost quest. This sort of helps block cheaters who might just copy stuff they see in chat.
Other things you can customize are the levels, how much XP is needed to advance, the titles of each level,
Let me know if you need more tips. I beta tested the quests extension for Bib and use them extensively on my servers.