Smog, the short and simple is that you add tippet when the tippet section of the leader is almost out. If you don't have the original package the leader came it then you will have to guess its exact lenght. Probobly about two ft. should do fine. When you get to that point or 6in before add another 1.5-2 ft of 5x tippet. You can google tons of pages on building your own leader that give explanations on how tapered leaders work and formulas for repairing them as well as adjusting aspects such as tippet lenght to get a better cast. I would highly reccommend checking afew of them out. this one may be a bit too complex initially but shows for different lenght and tippet size how to build a leader from scratch. If you look at the numbers the thicker diameter sections called the but then it tapers down in size through the middle section ending up at the tippet. On a tapered leader like yours you will quickly run through that tippet section that was built into the original and need to replace it with an equal amount and diameter material i.e. 5x tippet. http://www.hookhack.com/handtiedleaders.html
. Hope that helps. If your fishing for all of those fish you will definately want to try and learn much more about leaders and how they perform for the various types of fishing you want to do.