Unfortunately, what you are looking for has no single nor quick solution (assuming you want quality results). There are many ways to achieve this, so that is why you see different techniques. You could use QuickMask, or Select->Color Range, or use different channels, or third party apps such as KnockOut, or Image->Extract, or...
There are plenty of tutorials out there, just find the one that best fits your image (since many of the techniques are useful for certain types of extraction) and also make sure they are for the version of PS you have (or close to it) since some techniques are now outdated.
The most easiest and effective way (but also a time consuming one) to extract a person out of a picture is to work with the polygonal lasso tool (or pen tool).
Press "L" (shortcut for lasso tool) and add lines around your person by clicking on the edge of your object (the closer you click the smoother curves are, just like 3D objects). Once the person is selected, right click and choose "Layer via copy". Now theres a new layer with your person. click the eye in your old layer so your person will have a tranparent background. Now use a soft brush not bigger than 15 px and smooth/remove excess edges. now you can drag the layer to your new background image.
hope it helps,
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