your primary plastic vessel sounds flaky... you want a controlled airlock, not one that is leaky.... I would buy a rubber bung with a hole for the glass carboy and some plastic tubing from the hardware store and run the tube into a milk jug half filled with water (with a *small* amt of bleach) and ferment in the glass carboy instead... its more fun to be able to watch it bubble, churn and ferment anyhow...
if its your 1st batch, don't worry about the secondary stage...
just keep it away from sunlight in a closet or throw a towel over it... only fill the carboy up ~85-90% with beer or you will have lots of blow off (which is ok, if your water jug can contain it)... the first time I used a 5 gallon bucket for the blowoff water interlock (this is overkill)... you will learn the proper headspace to leave in your primary vessel over time...