There are a few ways to run Windows on Mac.

Firstly, an additional partition in the Mac hard drive with Boot Camp should be made and an additional Windows operating system should be installed. It is possible to install Windows directly on Mac because it uses Intel processors.  Macs with Power PC processors cannot have an additional Windows partition because Windows OS simply will not run on Power PC processor.
So, if we have a Mac with Intel processor, there are two possibilities of installing Windows on Mac.
A partition with Boot Camp has to be made at first.
The second thing to be done is installing the virtualization software, such as Virtual Box from Oracle. It is explained in another article how to do it.

Also, there is commercial software that offers virtual Windows installation on Mac, but, I personally, find Virtual Box the best for virtualization.

It has to be mentioned that during the Windows installation on the separate partition on Mac that partition must be formatted to NTFS. Otherwise, the Windows installer simply will not work.

This problem was reported by some users. The explanation is that the Boot Camp partition must be reformatted into NTFS.

Here is the step by step guide of how to install the Windows on a separate partition on Mac.
One more thing to mention is that a Boot Camp hard disk must have only one volume if it is to be used. If it has more than one volume the Boot Camp will suggest joining it into one volume. It is unusual, but this is how the Boot Camp works.

Here is a step by step guide of how to install the Windows on Mac as a virtual operating system using Virtual Box.

Good luck with this!

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