Zim is a graphical text editor used to maintain a collection of wiki pages. Each page can contain links to other pages, simple formatting and images. Pages are stored in a folder structure, like in an outliner, and can have attachments. Creating a new page is as easy as linking to a nonexistent page. All data is stored in plain text files with wiki formatting. Various plugins provide additional functionality, like a task list manager, an equation editor, a tray icon, and support for version control. For more information visit the Zim Information page.
1.) Update System.
It is always best to make sure that your system is up to date before installing any new software. Open your terminal (CTRL+ALT+t) and enter this command to update and upgrade your system.
$ sudo apt-get update && sudo apt-get upgrade