Where are you and what plants do you have? Being so vague we can't help much.

Im in southern ca. The plants I have are: a Sarracenia purpurea, a Drosera capensis, and a Pinguicula. The dimensons of my cylender terrarium: the diameter is 8 in and the height of 12 in.

In my pitcher plant I had put some water in it because it didn't have any water. However after reading a bit I learned the pitcher plant will automaticaly fill itself with "water". So I dumped out the water. Will my pitcher plant be ok? Also all my plants have dirt on their "bug catching leaves" will they be ok?

PLEASE reply quickly because some of the plants are suppose to be hibernating in a couple of weeks.

Not in southern CA.

Why did you dump the water out? Rain is what fills purpurea pitchers.
All your plants would probably do fine outside for the winter but keeping excess water out and allowing airflow in will be the challenge. Propping a slightly larger piece of glass or plastic above the terrarium would work to keep rain out and allow some air flow to keep it from over heating in the sun.
I would separate them and put them in their own pots.

I dumped out the water because one website said that the pitchers produce their own special smelling "water". Also the pitcher is starting to get brown, its preparing for hibernation isn't it? And one website said the pitcher plant NEEDS the hibernation or else it will not return to normal in the spring. At the moment I don't think I should seperate them because I have just moved them so they might die. Should I keep them inside or outside for the winter? Should I seperate the sundew and try to hibernate the plants? Sorry for all the questions, I'm a new CP owner. THANK YOU FOR ALL YOUR HELP!

Sarracenia purpurea is an outdoor plant

Drosera capensis and the Pinguicula do just fine at a sunny window sill, with their pots in an inch of distilled water.

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I don't get much rain or humidity in my area though.

Can you buy gallons jugs of distilled water? Walmart sells them for 86 cents.

You need to do your best to separate the purpurea from the other 2 for 2 reasons. One the pitcher plant needs a cold dormancy(not hibernation) and two the soil needs to be kept dryer for that dormancy. Like I said before you could probably keep them all outside for the winter in S. CA. but with this years summer(or lack of) who knows what the winter will be like. Use a spatula or something similar to remove the pitcher plant with minimal root disturbance and put it in it's own pot.

I'll do that and does the pitcher plant still need to eat during dormacy? Also can I put the pitcher plant back after dormacy?

How well would these plants work in my terrarium? Like do they hibernate or are they year round?

http://www.californiacarnivores.com/nrafflesianawhitewredspotsdeluxepottedl-tc.aspx

http://www.californiacarnivores.com/nsanguineapinkdeluxepottedm-tc.aspx

http://www.californiacarnivores.com/dspathulatadeluxepotted.aspx

No they don't need to eat during dormancy. Why would you put it back just to disturb it again next year? They shouldn't get disturbed until dormant if at all possible.
Those will all do well in a vented terrarium for the first year or 2 but what will you do with the nepenthes when they outgrow the terrarium? S.CA. is a little too dry for them unless you use a humidifier.

Thanks Ill just not buy the nepenthes then. Also do pitcher plants need sunlight during dormacy because I was planning to put them in the veggie section of my refridgerator? If so what should I do?

They don't need light when dormant. You could type dormancy in the search box at the bottom of the forum page to bring up lots of info on dormancy and the different ways of providing it. Here's a thread where I describe what I do for frige dormancy but you'll find other threads with much more detail from me and others by doing the search.

Here is a link that might be useful: Issues I ran into last winter..mold!

There are a variety of approaches to dormancy. Ideally, if your area is cold enough without being too cold, outside would be best. Some of us live in the South and getting temps cold enough is an issue. So many folks use a fridge. For us in the North, the plants would freeze to death outside. So many of us use attics, garages, heavy mulching outside, and fridges. When my collection was small I had my 2 VFT's in the butter keeper. When we moved to a home with an upper and lower, with attic, I used the attic. it was cold enough, here in Western NY, to be in an unheated attic, but the heat from the 2nd floor kept it from being as cold as the outside. For a couple years I had to farm my collection to a co-worker's garage. This year I will be borrowing space from a wholesle greenhouse. One thing an attic with window does, though, is provide the cues for the plants to break dormancy, since they will respond to the increased daylength of mid-late winter. Light isn't necessary but it's more natural for breaking dormancy.

I was woundering about feeding, I was planning to feed my CP wingless fruit flies. Should I manually drop them on/in to the plants or should I just put them into my terrarium, close the lid and home the plants eat them? Also how many flies should I give each plant/leaf/pitcher?

There is no need to feed the plants. IF you want you could drop on or two in a few pitchers but there is no need.

My plants are in a terrarium mostly closed terrarium and I was also wondering what about the Drosera capensis and the Pinguicula.

In lieu of live prey you can buy a cannister of freezed dried bloodworms and crush them before feeding plants with sticky surfaces, like the capensis (sundews) and butterworts.