Scheduling activities and resources on a project can be supported with GANTT or PERT diagrams. There are many software applications for that. I suggest to try two open source products.

OpenProj is is a desktop replacement of Microsoft Project. OpenProj has equivalent functionality, a familiar user interface and even opens existing MSProject files.
GanttProject hides many useful features that make it suitable for a wide range of project planning activities and allows you to share your projects with other users, which makes it a good tool for workgroups.
Both are free of charge and can be downloaded from Sourceforge.