When we witches ground ourselves, it doesn't mean we have put ourselves in time-out and banned ourselves from going out, using phones, internet etc. It describes what we do to reconnect ourselves to Mother Earth. There are many techniques you can use to do this, but I have always felt most comfortable with this one:
Take a few minutes to relax yourself. Slow your breathing down to a normal rate and just feel the tension flowing out of you. As you allow the tension to flow out of you feel your body becoming relaxed and loose. If you haven't already closed your eyes now is the time to do so. Spend a little while longer, with your eyes shut, just feeling relaxed and at peace.
Now, visualise yourself standing outside on the ground. Feel your feet physically connected to the ground and then imagine that roots are emerging from the souls of your feet, reaching down into the ground below you. See those roots reaching into the centre of the earth and taking hold. As these roots take hold, feel the power of Mother Earth flowing back into you through your roots. Spend as much time as you need doing this exercise and when you feel ready, slowly come back into yourself by slowly becoming more aware of your surroundings.
You can also ground yourself by working in a garden, feel the soil in your hands. Rubbing your hands in the soil connects you to the earth, as does working in your garden, weeding, clearing leaves, planting flowers etc. Also going for a walk in nature is a good way to feel grounded.
There are many techniques, including the use of certain crystals, opening chakras, or even eating certain foods, but the methods I have described are pretty simple ways.