Hi Lyes,
First off, welcome to the OUR forum~

Regarding concentration exercises to meditate, there are a several ways to go. Since I was trained in Zen back in the 90's, I tend to do an approach whereby I
'follow the breath'. This is set forth in a great book by Robert Aitken entitled:
Taking the Path of Zen and last I checked, was about $2.29 US dollars used, and new from $5.59. see:
http://www.robertaitken.net/ and also the Amazon website.
Also, you can obtain the
Abyss download. Try
http://www.binauralmindpower.com/ It is very helpful in getting you to a meditative state. You also may want to check
http://gnomad.info/All the best,
Nick