 Mast and Sub projects require a blank project and then individual projects which can then be inserted into the blank project. So here we've got four projects. Car servicing is the blank project and then car one, car two and car three are all about servicing cars and these will be inserted into the blank project. Now the master project is the blank project so we're going to open up car servicing and now we're going to insert the three individual projects. So I'm clicking the task name column. Project tab. Insert section of the ribbon towards the left and sub project. Need to find my files now. And I'm going to insert car one, car two.