I recently bought a NW800 condenser mic and phantom power. I was using audacity to record directly into my Acer laptop that has a dual input. It records well but is extremely quiet even with the phantom power and when i amplify the sound it decreases the quality. I am new to condenser mics and recording so if anyone could help it would be much appreciated.
I suspect this is because you're not using a microphone pre-amplifier or pre-amp.
Microphones provide an output that is quite low compared to line level and also have high impedance which means they cannot provide a lot of current and will get loaded by the circuit they are connected to.
Pre-amps perform the dual task of provining a high impedance connection to match the mic's and to amplify the (current of the) mic signal to line level.
Many sound cards provide one or more input channels with pre-amps but as far as I know, laptop onboard sound cards don't.
I watched a review of the NW-800 and found surprising that they provide an XLR to 1/8" jack because the way I see it, this is like encouraging the user to make a connection that won't work. All pre-amps I have ever seen have an XLR input and the output, being on line level can be either 1/4" or 1/8" jack.
They may have a different way of running things for consumer electronics or there might be something I haven't understood about this mic but I would never use it the way they are suggesting.
I would use a soundcard with pre-amp(s) and phantom power (+48V) and use it like any normal condenser mic, uning an XLR to XLR cable.
I feel like what you are trying to say is: "I recently bought a NW800 condenser mic that NEEDS phantom power."
Phantom power isn't something a mic has, it's something that is fed TO the mic in order for it to work properly. If you're going directly into your laptop, I doubt it's sending back phantom power. In fact, thinking about it, laptop power supplies are usually around 12 volts, so it would obviously not be able to provide the 48v that your mic needs. Like Schizomorph said, you need a preamp between the mic and laptop. Best would be a usb interface, just for ease of use.
This is obviously an electret condenser microphone that doesn't use phantom power for polarization but rather just uses it for powering a FET preamp. This means that the FET preamp should work fine when you provide it with "plugin power". Most laptop microphone inputs can deliver that but it may be switched off by default. See whether you find a utility that allows you to switch it on or increase the bias voltage (under GNU/Linux and the typical AC97 codecs this is hdajackretask for enabling parser hints, double-clicking on jack-modes until they are on, then using alsamixer for setting the bias voltage, likely to 80% of the reference voltage. Cough cough).
In other words: you'll stay mostly new to condenser mics after working with the NW800 since neither its default operating mode with the delivered cable nor its noise levels would be significantly related to what one can expect from using a condenser microphone. On the plus side a true condenser would be unusable on a laptop microphone input, both because of the laptop providing too little voltage and the microphone providing too little output.