Blender is a graphic art program that allows you to create 3D artwork on your computer. Items and shapes are made of connected vertices in Blender. When two items are joined together, their vertices are linked. You can select the linked verticies and use keyboard shortcuts to unjoin the two items. This allows you to edit and texture the items as individual pieces.
Press the "Tab" key to enter Edit Mode.
Right-click on the vertices that connects to two items to select them. You can also press the "Ctrl+L" keys to select all linked vertices.
Press the "P" key.
Click "Selected" from the menu when prompted. Blender will unjoin the two connected items.