Thomas from the code that you just added it doesn't input the name nor password into the BSTree anywhere.
To add your second question that would be an easy fix just add something that asks the user how many users and passwords they would like to enter capture that number and loop through.
double holder = 0;
System.out.println("How many users would you like to enter?")
holder = userInput.nextDouble();
for (int num=0; num<holder; num++)
// rest of your code