First, we cannot really “shut off the mind” because our brain is hardwired to think thoughts all the time. The goal wouldn’t be to shut off the mind but over time, with regular meditation, you can learn to quiet the mind, body, emotion and spirit.
There are many different types of meditation out there. I would recommend researching them, exploring them and trying them to find the best one for you.
Some of the ones I do are guided imagery, mindfulness meditation, counting breaths, and being aware of the senses.
The simplest one you can try would be to sit upright comfortably, legs either in a lotus-like position or with feet on the floor. And you will just close your eyes and focus your attention on your breathing. Focus on the in breath, the out breath, and try to slow the breath down a little. You can focus on following the breath as it goes down to the belly and back out.
And you can do this for anywhere from 5 minutes to an hour or more. It can be a good place to start.