If there are no text elements selected then changing the text rotation will set the TreeDraw default text rotation (applied to new text elements). Otherwise the rotation chosen is applied to all selected text elements.

Select the text element(s) you want to rotate and use "Format | Text rotation" from the main menu. The Text Rotation dialog will open. Enter the rotation you require in the Degrees box or use the up/down arrows. Rotation is measured clockwise from the horizontal. To quickly set a rotation of 0, 45, 90, 135, 180, 225, 270 or 315 degrees click on the appropriate segment of the text wheel. Double-clicking on the text wheel sets the rotation and OKs the dialog.

With only one text element selected it will have small black handles around it like this:

and the Status bar will show "Selected: 1".

Move the mouse cursor over one of the handles. The cursor will change to showing that the mouse is over the handle. Hold down the right mouse button, the cursor will change to and the status bar will show the degree of rotation. Drag the text handle until the text has rotated to the angle you require and release the mouse button.