How can I get Microsoft paint on iMac

There are other paint apps that work similarly to MS Paint.

You don't necessarily need MS Paint on your Mac.

Here are some simple paint apps for OS X.

Paintbrush

http://paintbrush.sourceforge.net/

My Paint

http://mypaint.org/about/

There are other simple paint apps in the Mac App Store.

iPaintX

Quick Paint (looks alot like MS Paint)

Microsoft Paint runs on Windows. You would need to install Windows on your Mac to get Microsoft Paint.

No other way to do this.

FWIW, PlayOnMac (free) does support Microsoft Paint if that's really your heart's desire…

https://www.playonmac.com/en/supported_apps-6-0.html