Start back at the beginning. Front mech first. Undo the cable clamp on the mech and then ensure the shifter is released, ie that it is in small cog setting. If you haven't moved the mechs position or limit screws leave them well alone. Now, wind the barrel adjuster all the way in, then back it off a half turn. pull the cable through the cable clamp to take up all the slack and clamp it in place. Now, turn the pedals gently and try to shift from small to big. If it does it smoothly and quickly you've cracked it. If it doesn't quite go up quickly and smoothly, use the barrel adjuster to add tension to the cable until it does.
Once that's working shift to the back and once again, put the chain on the smallest cog, undo the cable clamp, shift to smallest shifter position ie release the shifter. Wind the barrel adjuster all the way in then back out half a turn. Again, if you haven't messed with the limit screws leave well alone, and this time pull the cable through the clamp as tight as you can by hand, you need to take all the slack out. Use a pair of pliers to get more of a grip.
Now, with the chain on middle ring turn the pedals and try to shift to the next cog. Once again, it needs to move smoothly and quickly from first to second . If not, add tension a little at a time using the barrel adjuster , remembering to click, then release as you do so, so each time you are trying to achieve a smooth fast change with one simple click of the shifter. Once you have got it shifting up a cog properly, try the shift up to the third cog from the second, and then ensure that the shift is one click per cog all the way to the biggest one.
Now you need to check that it comes back down cleanly and crisply, again, one click of the release for one drop down the cassette. Make fine adjustments with the barrel adjuster but don't go so far that it stops shifting up,properly. Bit of trial and error and patience helps here.
Finally put the chain on the big ring and check the changes are smooth up and down the same. In future, now your cable has stretched and bedded in, yo will only need to make fine adjustments using the barrel adjusters.
