How to solve system of second order equations in matlab using ode 45

Hi everyone I have a system of second order equations including seven equations.I want to define a function named F describing the equations and then use ode45 function. first I don't know how to write the function, second I don't know how to write 14 boundary conditions in the form of [t,y]=ode45(@F,tspan,BC)in ode45 command. thanks