dhAra is flow. dhAraNa is to hold an idea, or a thought.
dhru word root means to bear. dhAryatE means bears.
Having practiced restraint from undesired things and commitment to valued principles, having found a comfortable posture that you can hold for a long time, having practiced breath regulation and having learned not to pay attention to the data stream continuously presented by your senses -
you know practice holding one idea in your mind.
That could be Aum, or Rama Nama or the form of Vishnu or a Divine Light or the idea that Everything is Brahman or that You are He.
Some people constantly hold on to the idea that the people they are forced to live with are not nice in behaviour or ideology or such like. These are people who become very unhappy and distressed.
There are people who hold the idea that “Rama is perfect” or “Lalita is gentle” or “Hanuman is pure” and so on. These are happy people always laughing and energetic.
The idea that “sarvam brahma – all is brahman”, and “pUrNam adah pUrNam idam – That (para) is complete and this (iha) is complete” and “soaham asmi – He, I am ” give peace and tranquillity and open the way to greater knowledge.
The world has been presenting us various ideas often conflicting, since birth. At different times, different ideas and arguments appeal to us. Some make us depressed, some make us excited and some make us illumined.
Only those who have practiced detachment can accept the idea that all is brahman, and that includes me.
On holding this idea and becoming detached to the idea of mistakes and achievements, and recognising that the real doer is the brahman, those people attain inner peace – s’ama.
Now is the time for dhyAna or paying attention.
You may pay attention to your various chakrAs, or to the idea of your iSTa daivam. Each has its own effect on you. Different gurus suggest different ways of becoming calm and different things to focus on so that you can attain that ultimate state of bliss. You can pick what works for you.
Remember that the mind need not be crushed or controlled or supressed, it just needs to be calm and still like your body, like a clear lake on a beautiful, cool windless day.