First, get your screen calibrated. Only then the screen will show what is encoded and described in the image data. Many screens come with some factory calibration, but that only covers the screen. Your computer and its settings are not included. Therefore, it is best to get a screen calibrator that does the job directly on your computer and screen together. Personally I use Spyder 4 from DataColor, but there are are other tools as well. Check the websites for details, for a single screen without print calibration the basic model is sufficient. For dual screen and print calibration you need the higher end versions. You can get them online or from local stores. Once this is done, you can start adjusting the white balance.
Here, it starts with your camera settings and the file format you are working with. Most cameras get a decent white balance in Auto setting. Only if you have mixed light setups (different types of lights, flashes involved) or some objects with a very distinctive color (pink background wall) you might need to adjust the settings.
You can use a grey card or white card and follow your camera settings to do the adjustments directly. These cards will act as reference for difficult scenes to get you within 95% range, the rest is a small adjustment later in post processing.
For full adjustments in post processing, or for creative and special effects you best shoot in Raw format (see camera manual for settings) and use post processing software (one comes with your camera, others are the usual suspects from Adobe: Lightroom and PhotoShop, or other programs). Once the image is loaded, there are pick tools which you point to white or grey objects. From there the tools will determine the necessary adjustments to get neutral white balance. The rest is up to your taste. Keep in mind: a technically clean and neutral WB is often perceived as cold, wee bit warmer works much better.