When loading into the game with the QuestLoader you should see a new window open up next to REFramework. That is basically the entire interface for the quest loader.

You can export existing quests with the "Export Quest", or "Export All Quests" button. To export a specific quest simply enter its ID in the box and then click "Export Quest".

Exported quests will be saved in reframework/exported_quests/.

In the Quest Loader tab there is a "Reload Quests" button to reload quests while in-game.

There are also 2 lists, the first one is for replacement quests, i.e. quests that overwrite an existing quest in the game. There is also a checkbox next to each replacement quest. This determines if the quest if active or not. If you remove the check then the original quest will be active.

The other one is for fully custom quests that don't replace anything. Next to each custom quest there is an "Unload" button if you want to unload that quest.