# Organizing Groups and Sections
The **Assembly Instructions** are organized in a tree structure similar to a family tree. They are displayed in the **Section Assembly** panel, located beneath **Available Sections**.
The tree begins with a single root node at the top, from which multiple branches may extend. Branches are created by adding and nesting **Groups**. These branches are indented and color-coded to indicate their structure.
Separate assembly trees are maintained for warp and weft. Additional trees are also available for warp and weft color assembly when color is not inherited from the drawdown.
To begin defining section assembly instructions, a **Group** must first be added.
### Adding a Group
Group Icon (3rd from Left)
The **Group** icon is highlighted above (third from the left; it appears as a document with a dark blue heading). Pop-up descriptions for each icon are displayed when you hover over them.
Click the **Group** icon to add a group. If no groups have been previously defined, a **root** group is created automatically, as shown below.
There is only one group at the root level. Any additional groups that are added become children of the root group, as shown below.
Showing a second Group
### Adding a Section to the Assembly Tree
A section can be added to the Assembly Tree using the following steps:
1. In **Available Sections**, click to select a section. An arrow will appear to the left of the selected section.
2. In the **Assembly Tree** below, click to select the location where the section should be added. This may be a group header or another section.
3. Click the **Add Section** button (second from the left).
Alternately, sections can also be added to the **Assembly Tree** by **dragging** them directly from Available Sections into the desired location in the Assembly Tree.
