Steps to make watermark in PS:

01. Open the picture, enter text, and choose the font you like.

02. Load the text into the selection, hold down the ctrl key, and click on the thumbnail of the text layer.

03. Execute the Select-Save as Selection command to save the selection as a new channel and name it watermark.

04. Execute the Select--Deselect command, and then delete the text layer. Enter the channel palette and add a copy of the watermark (drag the watermark to the position shown in the icon to add a copy). Use the keyboard arrow keys to adjust the watermark copy. Press and hold the ctrl arrow key ↓ twice and → twice.

05. Return to the layers palette and create a new layer. Execute the Select--Load Selection command and select "Watermark" for the channel.

06. Execute the Select--Load Selection command, select a copy of the watermark, and subtract it from the selection.

07. Execute the Edit-Fill command to fill the selection with white.

08. Execute the select-load selection command and select the watermark copy for the channel. Execute the Select--Load Selection command, select the watermark, and subtract it from the selection. (Contrary to steps 5 and 6)

09. Execute the Edit-Fill command, fill the selection with black, and change the opacity of the layer.