How to open taskmanager in Mac

Hey, Tina is just as simple as it you can just follow the path Applications>Utilities>Taskmanager

(Or) You can open your mac task manager by just searching on spotlight you can find there easily...

But remember in OS X taskmanager is called Activity Monitor

If you still have any doubt i have found a in-depth article about mac task manager-Apple Support

There is no Task Manager on Mac. The closet thing may be Activity Monitor in your Utilities folder. Here is list of Windows and Mac terms you may find useful:

macOS Sierra: What’s it called on my Mac?

Also see this Support Topic:

Mac tips for Windows switchers - Apple Support