To use the 4D Phasing feature, assets need to be assigned to various phases as necessary. The process for assigning a phase to an asset or object is the same whether phases are used simply for organization or for use with the 4D Phasing/GANTT chart feature.
Find the asset in the Organize hierarchy and click the three dots to the left of the asset name. If the phase has been created, select it from the drop down. If the phase has not been created, click Phase Name under the drop down and type the name of the new phase. Click 'New Phase' to the right to create the phase and the asset will automatically be assigned to the new phase.