Create text watermark :
1 ) menu "File" -> "New", set both width and height to 200
2 ) click right mouse button on image to pop menu, select "Cut"
3 ) add text : WordArt Topic
4 ) menu "Tool" -> "Batch Watermark", the text will appears in the watermark box

Example :
this example rotate text, set text layer's transparency to 50%, use Tile to fill watermark



Tips : batch convert image's format
remove step 3) , that is to use a complete transparent image as watermark, select output image's format, then we can start convert