Do you mean C1? Or C3? Because C3 is slightly more complex than C1 electrolysis.
But in C1 electrolysis uses ionic and regular compounds such as Aluminium Oxide and HCl, so for example:
HCl is used as the electrolyte which is what you're trying to break down. The electrolysis of HCl forms H+ (cat) ions and Cl- (an) ions, this is because Hydrogen has 1 outer electron so it wants to loose it and Cl has 7 outer electrons. Meaning Hydrogen looses an electron becoming H+ and Chlorine gains an electron becoming Cl-
So in the electrolyte you then have H+ cations and Cl- anions the H+ ions will move to the negative electrode (cathode) where it gains electrons due to reduction and because Hydrogen travels round in pairs its usually H2 meaning you need to gain 2 electrons (H2 -> 2H+ + 2e-) which means its released as a Hydrogen gas!
Then you have Cl- which is an Anion and it will go to the Anode, this is where oxidation takes place meaning it looses electrons, Cl2 usually travels round in pairs again! so 2 chlorine atoms will need to loose to electrons (2Cl- -> Cl2 + 2e-) and this means Chlorine is released as a gas!
So the D.C electric current basically takes electrons from the Cathode and supplies them to the Anode (hence positive and negative)
I hope this helped you!