Grounding is easy to do and something I STRONGLY suggest learning and practicing regardless of your religious or spiritual beliefs.
Do you ever feel a bit "spacey" or not quite "here"? this means you are not grounded, grounding is also useful when you feel emotional, whether sad, angry or too overjoyed. Grounding basically brings you back to reality and stabilizes you in your body and anchors you to the Earth.
So HOW do you Ground yourself?
There are a few different ways to do this, I'll list the most common and easiest way here...
The best way to do this to be seated on the ground itself, not always practical and not necessary, but for the best results I suggest trying it at least once to really feel it working.
Clear your mind as best you can, then focus and imagine all the negative thoughts, emotions, confusion etc. joining together and forming a ball of energy, I generally see the energy ball in my stomach. Then as it grows you want to visualize it moving down into the Earth itself, deep down into the center of the Earths' core.
Visualize the Earth core burning this energy ball up and turning it into a new ball of positive energy, a bright white light (or gold or blue whichever works for you) which is full or positive emotions, thoughts and energy.
Then see this new positive energy ball move up through the Earth and into your body. As it becomes part of you you are filled with positive energy. Repeat the steps, realeasing negative and drawing in positive until you feel calm and collected.
Another method is the "Tree Roots" method. I personally prefer this to the Energy ball, but it could be because I often ground myself while walking or out in public and find it easier and faster.
Start the same way, clear your mind and focus. This time you will imagine or visualize a cord, roots (like tree roots) or energy shards (like lightning) which come from your body and go deep into the Earth, into the core.
The cord, roots or shards you have visualized now act as a freeway for energy to flow between your body and the Earths' core. Draw up all of the negative thoughts, emotions and confusion etc. and push this energy down through the path you created and into the Earths' core. Then the same thing as before, see this energy transform into positive energy and draw it back up through your pathway and into your body.
Again, repeat this until you feel calm, collected and "heavy"
The feeling of being "heavy" means you have grounded yourself successfully, it can be a weird feeling at first if you've never felt it before. I compare it being anchored, like a boat to a dock, but you have anchored yourself to the Earth itself.
Once you get the hang of it, you can practice grounding anywhere and at anytime. If you're feeling stressed at work, or in line at a shop or bank just ground yourself and see how much of a difference it can make!
You don't need to be sitting down, you can ground yourself while walking, even driving (maybe not until you get the hang of it lol)
Image found on Google search some time ago, apologies for not having the original source listed, If I find it I will update the article.