On the Gantt Page, Manpower Requests are located at the bottom of each project area. The open requests section is highlighted in blue at the bottom of each applicable Project section. You can also find requests faster by applying the "Only Show Requests" filter.
To fill a request, simply click anywhere on the color bar for the particular request. This action will bring up the Request details, along with the Fill Request drop-down.
Once you have selected a resource from the drop down, this person's Assignment window will allow you to see if there would be any overlapping Assignments, should they be assigned to this Request.
You can Save the assignment or Save and Alert to send the new assignment details to the assigned person. Once you're done, the assignment will populate in the Projects area of the Gantt Page.