You can convert a curve or shape (path) drawn using the Pen into a selection. When created from a curve, the resulting selection will be closed using a straight line between the end nodes.
To create a pixel selection from a drawn line or shape (path):
Do one of the following:
Using the Pen draw a curve or closed shape on your page.
Select a previously drawn curve or shape and then select the Pen Tool.
Pixel selections from shapes