Objects can be rotated in a few different ways. So I would suggest trying them to see what suits your needs best. First, in the Parameter Tab, under the General Item will be a list of transforms. Rotation can be accomplished there. Also, under Tools on the Menu Bar is the Rotate Option (The Rotate Widget will appear in the Viewport), and the Universal Option (which displays a widget in the Viewport to do Transform operations including Rotate) Also there is the keyboard short cut (Alt-Shift-R) which displays the Rotate Widget.

Hoe that helps and gets you started. Jack238