As far as HOW to do these things, you'd do yourself a favor by buying a low cost manual (Haynes or Chilton) for your car. They can be had for about $13. Try eBay. There's too much information you need for one person to post on this website. In these manuals they have procedures and good illustrations to show you where everything is and what needs to be done.
If you don't understand something in the manual, or if the engine still doesn't perk up after the tune-up, you can always post here... we'll help direct you further.
95 E320 Cabriolet, 131K