how to apply runge-kuta 4th algorithm for my equation

Hi dear friends, I have a heat equation and want to solve with RK4 but I don't know how I can apply a RK4(runge-kuta) algorithm. i attached the equation I solved first and second part with an initial value and now i should solve it using RK4 algorithm. shall you help me please? my initial value would be a vector and time step in 10 sec

thanks in advance