2. Mask the image with a soft edge of about 50 (for details see automask) and select the 
Draw Tool from the tool bar. Then press Work On Whole Picture at the tool options 
dialog.  
 

You get something like this: 
 

3. Now create a new Layer (Layer/New Layer) with the size of your text and move the layer to the place where your text should be placed (use the Layer Move Tool from the tool bar)  
 

4. Set a foreground color that you want for the background of your text, for example red. Then  select the Draw Tool once more again and press Work On Whole Picture. You get something like this:  
 

5. Now select the Text Tool from the tool bar.  
 

Select the Font and color you wish and type the text at the Tool Options to the Text Tool. Then press Set (be aware that the text will be placed with the foreground color). 
Move the test in the image to the box and double click on it. Then press CTRL-D to deselect the text lasso. 

6. Now change the intensity of your layer at the Layer Panel to 50%. And when your ready, select Layer/Reduce to Background Layer.