How do i know which side of ceramic capacitor is positive?

Ceramic caps do not have polarity.

ceramic capacitors are normally polarity indifferent, they don't have a + or - lead.

not all caps are polarized so in this case it does not matter.
Flat caps are typically non polarized, while can shaped ones are and are usually painted or shrinkwrapped with polarity indicated.

No, it does not matter which way you place ceramic capacitors.  These types of capacitors have no polarity.  Generally, electrolytic capacitors (mainly aluminum and tantalum) are the types associated with polarized capacitors, and they will usually have a "+" sign on the sleeving, or a stripe with "-" signs on the sleeving, indicating its polarity.  So basically, no, you're fine putting the ceramics in the circuit in either direction.

Ceramic capacitors have no polarity.

The black marks on some of them may indicate that that lead is connected to the outside foil (of the spiral-wrapped foil conductor, insulator, foil conductor "sandwich"), in which case it would be wise to put that lead at closest to ground potential.

Back in the days of tube radios if the outer insulation was ever scratched and the outer foil was accidentally shorted out to chassis, there would be no damage done (it would be a ground to ground connection).  If the outer foil was mis-connected to a positive high voltage and the same scratch and short to chassis occured, then sparks would 'fly' and other parts would be damaged.

In low voltage, low current applications, especially when the components are on PCboards, it makes absolutely no difference how ceramics are connected.

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