using max power transfer theorem to calculate the value of the Rload
The Maximum Power Transfer theorem states:
The load resistance that absorbs the maximum power from a two-terminal circuit is equal to the Thévenin resistance
Do you know how to find the Thévenin resistance of a two-terminal circuit?
I'll give you a start. You have to find the equivalent resistance seen when looking into the terminals of your circuit, with \$R_L\$ taken out and your voltage source shorted.

Can you take it from here or do you need more help?