Tell you the steps of watermarking with ps:

0 1. Open the picture, enter the text, and choose your favorite font.

02. Load the text into the selection, hold down the ctrl key, and then click 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 as a watermark.

04. Execute the select-deselect command, and then delete the text layer. Enter the channel palette and add a copy of the watermark (you can add a copy by dragging the watermark to the position shown in the figure). Use the keyboard arrow keys to adjust the watermark copy, and press and hold ctrl+ arrow keys ↓ twice → twice.

05. Return to the Layers panel and create a new layer. Execute the Select-Load selection command to select "watermark" for the channel.

06. Execute the select-load selection command, select the watermark copy and subtract it from the selection.

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

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

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