diy sump/overflow

[LostLoach]

ok so i want to build my own sump iv been checkin out some videos on youtube and i think the best wat for me would be using like a plastic storage bin with a 5g bucket i dont quite know how the whole thing works like how do u get the water to flow down to the sump i know you use a pump to return flow but yah please help me out any help or advice will be greatly appreciated.its a 55 gallon tank
thanks-david