Stamp your mark all over your pictures and create watermarks in Elements
Open the picture you want to add a watermark to, and select the Shape tool on the left-hand panel. Click the line option and set the width; fairly light should be enough, so pick anywhere between 5 and 20px. Drag two white lines from one corner to the next to form a cross like we have here.
Paste the logo for your watermark into your picture. Make sure that it is white to match the lines that you’ve created already, and that the logo is cut out from its background. Drag it to the centre; use the central marker in the selection to align it with the intersection of where the two lines cross.
Click on your logo layer. Go to Layer>Layer Style>Style Settings and add a Drop Shadow of Size: 100, Distance: 5 and Opacity: 25. Click OK. Now Ctrl/right-click this layer, click Copy Layer Style, Ctrl/right-click the other two layers and hit Paste Layer Style. This will add this exact drop shadow to every layer.
With the watermark almost complete, we just need to get rid of the lines’ intersection behind the logo. Hit the mask icon on both Shape layers and pick a big, black brush the size of your logo – either soft or hard, depending on the effect you want. Move your brush to the centre of the picture and click to erase.