there are 2 fuse boxes, one under the hood in the vicinity of the battery. the other box is usually on the drivers side either under the dash by your feet on the left, or where the door meets the dash. Occasionally it will be found in the glove box on where the passenger door meets the dash.
First thing to do is check the basics, oil level and coolant level in reservoir. (concerning the engine light) If the oil and coolant level is fine you should be safe to drive it to Auto Zone (or other such store, however Auto Zone does it for free) and have them plug in the computer to determine the cause of the engine light, it could be any number of things even the gas cap.
The tail light could be a fuse, however if no fuse is blown it could also be loose wiring. if you do not have an owner's manual, a really great investment is a repair manual, Chilton has the 1999 Forester online at http://seo.chiltonsonline.com/Pub/DIY/Product.aspx?ca=Repair&b=346
this will have step by step instructions on removing panels to check wires and replacing lamps.
check to see if the brake lights work and if they are a different bulb than the tail lights, I had a similar problem in an old Cavalier where the brake lights worked but the tail lights didn't, my problem was in the switch where you turn on the headlights/turn signal. Have a friend help determine what, if any, lights are working in the rear and front of the car.
Auto Parts stores have diagnosis equipment for common issues and are generally very helpful if you have a question about what may cause a problem. ( I have only had a problem with Pep Boys when it comes to being helpful.)
I wish you luck.