Hi Ndelilio, it's really great that you've started working on your engine yourself.
Now that you've taken the head off, DO NOT let those pistons move. Not even 1mm! Keep the car in neutral. The pistons are in a sleeve (liner) and there is a paper seal under the sleeve. If the seal is broken by movement of the piston, then you will get water flowing into your oil.
You should now also get a new gasket.
When you bolt the cylinder head back, they should be tightened with a Torque wrench to 45 foot/pounds and also in a certain order.
At this stage if you are going to work on your engine yourself, get a Haynes manual; it really does help
Good luck!