There are two steps that depend on your version of windows:windows 10/11 and the windows 8 and older way.
The windows 10/11 way
First step:Open settings
2nd step:Click on System
Last step:Click on about (1), Check System Type (2)
Now download 64 bit version of the program if your operating system is 64 bit,or download 32 bit if 32 bit operating system
Note:if your processor is x64 based but operating system is 32 bit,i recommend you to upgrade your operating system to 64 bit,if its x32 based,DO NOT try to install a 64 bit version of windows,as your computer will not boot up.
The windows 8 and older way
First step: Right Click on "My computer" Or "This PC"
2nd step: Click on "properties"
3rd step: Check to see if its 32 bit or 64 bit
Now download 64 bit version of the program if your operating system is 64 bit,or download 32 bit if 32 bit operating system