Upon turning on the washing machine, the water goes into the washing machine but is then flowing straight out the back pipe down the drain... causing the washing machine to never fill up!why?

The drain must be at the same level or above the washer top, that's how the water fills the washer-water seeks it's own level. Water does not flow up by itself, it has to be pumped out of a washer. Where is your drain located? If it's at floor level, the washer will never fill.