Equilibria: explain question

The synthesis of methanol from carbon monoxide and hydrogen is a reversible reaction that can reach dynamic equilibrium:

$$\ce{CO(g) + 2H2(g) <=> CH3OH(g)} \quad \Delta H = -90\ \text{kJ mol}^{-1}$$

Explain what is meant by dynamic equilibrium and why a closed system is necessary for equilibrium to be established. Using Le Chatelier's principle, predict the effect of increasing the temperature on the position of equilibrium for this reaction. Also explain the effect of adding a catalyst on the equilibrium position and on the rates of the forward and reverse reactions.