Let's go through some steps in adding text to this photo. Load your photograph into Pixlr X.
The very first menu icon is "Properties". Click on this to open the dialog box.
When you have completed your editing, click on the "Save" button at the lower right. Select "JPG" as the saved file type. Select the High Quality option, although even then, notice that it is still going to compress to about 90%. I would move that to 100%, so there is not much compression of the photo. The file will save to your browser Downloads folder.
Your final saved photo should look something like this. Play with the different properties to get an effect you want.
If you ever decided to remove the text, such as if you wanted to print this in a book, all you have to do is crop your photo to remove the text.
Hope that this tutorial was helpful.