In dhyana there is several types but this is the one very easy with chakra who are intrested in activating chakras and clean the power flow path .

this translated from Atharava Veda>  aatma rachana kriya shastra > baga 2 > iti chkra dhayanam 

Sit with your eyes closed, spine erect but not rigid 
Rest your hands on your thighs with palms facing up, 
index fingertips touching the tip of each thumb 
for the first three chakras, touching the middle joint 
of each thumb for the fourth & fifth chakras and the 
base of the thumb for the sixth & seventh chakras.
If you wish you may touch the tip of the tongue to the 
roof of your mouth. Take several long, slow, easy deep 
breaths breathing through your nose, until your body 
becomes calm. Sit during this meditation. Do not lie down. 
As we come to each chakra, focus your attention on the 
indicated area of your body. With each exhale chant the 
mantra that is given in a slow, elongated fashion. Begin 
with the root chakra (Mooladhara) and work upward to the
Crown (Sahasrara). At the end always allow the energy to 
ground, flowing down through your body, and spend a few 
minutes in meditation or lie on your back in shavasan.
 

1. Begin with the Mooladhara chakra, located at the perineum,

midway between your anus and genitals.

Say "Om Mooladhara".

Visualize its red color. Slowly repeat "Lang" (pronounced lung)

for a few minutes, then visualize the chakra turning liquid

gold as you say "Kundalini, arohanum" several times.

 

2. The Swadhisthana chakra, located in the genital

region or at the base of the spine.

Say "Om Swadhisthana".

Visualize its orange color. Say "Vang" (pronounced vung)

for a few minutes, then visualize the chakra turning liquid

gold as you say "Kundalini, arohanum" several times.

 

3. The Manipura chakra, located at the navel.

Say "Om Sri Mani Padme Hum".

Visualize its yellow color. Say "Rang" (pronounced rung)

for a few minutes, then visualize the chakra turning liquid

gold as you say "Kundalini, arohanum" several times.

 

4. The Anahata chakra, in the center of your chest,

your spiritual heart.

Say "Om Anahata".

Visualize its green color. Say "Yang" (pronounced yung)

for a few minutes, then visualize the chakra turning liquid

gold as you say "Kundalini, arohanum" several times.

 

5. The Vishuddhi chakra, located in your throat,

at the Adam´s apple or the epiglottis.

Say "Om Vishuddhi".

Visualize its blue color. Say "Hang" (pronounced hung)

for a few minutes, then visualize the chakra turning liquid

gold as you say "Kundalini, arohanum" several times.

 

6. The Ajneya chakra, located between our eyebrows.

Say "Om Ajneya".

Visualize its indigo color, the color of the original

Levi blue jeans prior to washing them. Say "AUM"

in a 3-2-1 ratio. "A-A-A-O-O-M" for a few minutes,

then visualize the chakra turning liquid gold

as you say "Kundalini, arohanum" several times.

 

7. The Sahasrara chakra, located at the center

of the top of your head.

Say "Om Sahasrara".

Visualize its violet color, pastel purple.

Say "Ogum Satyam Om" for a few minutes, then

visualize the chakra turning liquid gold as you say

"Kundalini, arohanum" several times.

after this biginers has to take rest for a while or do shavasana