Helpppp

It has 140,000 miles and it is loosing power. I took it to a dear and they hooked it up to a machine and told me that it needs a tune-up and yes the enging light is on. So YES i need to know where the spark plugs are and where I am suppose to put the boots

What you need to know is what were the trouble codes that they retrieve from the PCM. I'm pretty sure that there was more than just "spark plugs" to fix your problem. Get the trouble codes and I can help you. If you paid to have the car dealer to scan your VUE you do have the right to know the codes. Most likely there was a P0300 code and others. Just putting spark plugs in is not going to solve your problem. There's more to a "tuneup" than just replacing plugs and "boots". Unless you have a Fuel Injection Cleaner, you can't do this yourself. Removing & replacing plugs & plug boots, flushing the injectors & cleaning the air induction system replacing the fuel filter is worth about $300.00 to $400.00. I know you said you are not stupid, but think about what really has to be done on your VUE. I'm sure there's a independant auto repair shop that can give you a better price than the dealer.