How the combo works:
The main combo in the deck requires you to have a Juniper Order Ranger and persist creature in play (with no -1/-1 counters), and a Greater Gargadon suspended. Sacrifice the persist creature to Greater Gargadon. The card is returned to play from persist, and JOR gives him a counter. Because of rule 420.5n, the +1/+1 counter from JOR cancels out the -1/-1 counter from persist. With the "Remove a time counter from Greater Gargadon" ability still on the stack, sacrifice the persist creature to Greater Gargadon again. The persist creature comes back again, and repeat as necessary. The triggered ability of Murderous Redcap allows you to deal as much damage as you like, and the triggered ability of Kitchen Finks allows you to gain as much life as you like. Another possible combo requires you to start with just a Juniper Order Ranger in play. Play a Murderous Redcap, and target itself with it's ability. It comes back, the counter cancel each other out, the Redcap targets itself again. As a result, Juniper Order Ranger gets a +1/+1 counter from each time Murderous Redcap comes into play, leaving you with a gargantuan Order Ranger that's as big as you like.

Combos in this deck:

Juniper Order Ranger + Murderous Redcap (infinite Large Juniper) - redcap comes into play,shoots itself. dies. then returns with a -1/-1 counter. juniper gives it a +1/+1 and grows 1 size, and redcap shoots itself again correct? now recap is in grave but went to grave with a +1/+1 counter AND a -1/-1 counter.

Juniper Order Ranger + Murderous Redcap + Greater Gargadon (Infinite damage) - Juniper order ranger and murderous redcap in play.
Suspend greater gargadon.
Sacrifice redcap. Remove time counter effect is added to the stack.
Persist trigger is in effect and is added on top of the stack.

Juniper Order Ranger + Kitchen Finks + Greater Gargadon (Infinite Large Juniper + Infinite Life)

Juniper Order Ranger + Murderous Redcap + Brion Soutarm (infinite damage + infinite life, but you can take out only 1 opponent, for all the multiplayer rounds important) - You have a Brion and a Juniper in play. Then you play Redcap target itself, make Juniper infinite big and sac Juniper to Brion


Card Choices:

Glittering Wish is my Search engine, it fits in the curve and searches out all combo peaces but Gargadon, you can replace gargadon most of the time with Soutarm and glittering wish also helps to play a more midrange style deck.

Llanowar Reborn, gives my persist creatures more resilience.

Siege Gang Comando, is a solid creature anyway, but i think its worth mentioning that his synergy with Juniper is neat.

Analysys

Your problem match number 1 is faeries, where we have a good sideboard now, look in post 98 on page 7 to see how to side. Game 1 your the underdog, after siding it gets better.

The next 2 matchups that arent great, are dark mana ramp(with mindshatter and damnation) and counter heavy merfolk builds, but both are workable.

You are in good shape against aggresive decks of all kind, just dont force the combo. Its often better to play the card advantage game (combined with lifegain), then try to combo. Of course sometimes the combo just happen, thats also ok.