01 Install GanttProject
Since GanttProject is written in Java, it requires the Java Runtime Environment (JRE) in order to run. Make sure that the Sun JRE is installed on your system, then download and unpack the archive containing the latest version of GanttProject. Launch the application using the ganttproject.sh script in the resulting directory.

02 Set up a new project
To create a new project, choose Project>New. The Create New Project wizard will guide you through the process of setting up your project. Start with providing information about the project. Press the Next button and select an appropriate project domain. Press Next to move to the next step.

03 Specify holidays and weekends
To successfully schedule the project and its stages, you have to specify public holidays for your country and select the appropriate weekend days. If your country is not on the list, select none, and you can manually specify holidays later.

04 Define roles
Before you start adding users to your project, you should define their roles. To do this, choose Edit>Settings and select the Resource Roles section. Now specify as many roles as you need. For example, a documentation project may include the Writer, Proofreader and Editor roles.

05 Add users manually
Next step is to populate your project with users. To do this, choose Resources>New Resource and fill in the required fields. Note that besides general information such as name and email address, you have the option to specify days off for the specific user.

06 Import users from other projects
Alternatively, you can populate the project with users by importing them from another GanttProject file. Choose Resources>Import Resources, select the .gan or .xml file and press OK.

07 Using the Gantt section
The Gantt section in the left pane lets you specify project stages (or tasks in GanttProject’s terminology). Similar to an outlining application, the Gantt section presents project tasks as a hierarchical tree, and you can use the indent and move buttons to rearrange individual tasks. Each task can contain an unlimited number of subtasks, so you can break a larger project stage into smaller pieces, which gives you more granular control over the project.

08 Add a project task
To add a project task, press Ctrl+T, or choose Tasks>New Task. Give the task a descriptive name and hit Enter. Right-click on the created task and select Task Properties.