Creating my own Timer ( libgdx)

Heya guys! Im trying to create a class that i can pass the seconds i want it to wait as a param and every update of the Class that has the Timer as a variable, the update() of timer is called.

Heres what i have until now, its almost nothing but idk how to do it :

package br.tools;

/**
 * @author André Lopes
 */
public class MyTimer {

    private int currentSecond;
    private int secondsToWait;

    //Float Delta as param@ ???
    public void update() {
    }

    public boolean hasFinished() {
        return currentSecond >= secondsToWait;
    }

}