How Do I Thread A 5525 Singer Sewing Machine?

I have the same machine.  It took me forever to find a free reference doc/manual.  The only thing I could find was the threading guide.  The link below gives you tons of models to search for.  Look for the 5525 machine on the list.   Good luck.
www.mastersewusa.com

You can know this by reading the tutorial for threading a machine so you can check this website to possible get some help for machine threading.
www.sewingmachinemanual.com