zoko4ever :
@Geekwad
Can you tell how to do it and which paint should I use?
As others have mentioned, the tape out and covering of anything you don't want painted is the more important step. Completely cover the outside too....just to ensure any over-spray or aerosols don't blemish the outside.
For paint; any finish you're comfortable with (gloss, flat, etc) and a paint made for metal surfaces. Krylon or similar at a home/hardware store is just fine......just be sure to practice first until you're comfortable with how much to spray so that runs do not develop. Several light coats is probably the best method, as if you overdo it, the runs will be frustrating to get rid of.