An Activity is a place where work takes place on Work Items.
Work done at Acitivities usually takes up time and sometimes requires the availability of Resources. At an Activity a Work Item may be transformed in some way (perhaps by changing one or more of its labels). After the work is done the Work Item may be sent on to another simulation object, or one of a number of different simulation objects depending on routing rules that can be specified.
To create an Activity click the Activity button on the Build Tools toolbar and then click were you want the Activity on the simulation window.
Connect it to other objects using routing arrows.
To move an Activity: drag it on the simulation window.
To copy an Activity: drag it with the CTRL key on the keyboard held down.
To inspect or change the Activity's parameters double click on the Activity on the simulation window. This will open the Activity Dialog box.