How do I post data from a sign-up form to a specific collection in my mongodb server using mongoose

I was wondering how would I be able to push data from my sign-up schema to a specific collection in my mongodb server. I am working with PassportJS and I created a method for users to sign-up but it doesn't seem to be saving to my database. would anyone be able to help me with this?

    var mongoose = require('mongoose');
    var schema = mongoose.Schema;

    var usersSchema = new schema ({
      name: String, 
      username: String, 
      email: String,
      password: String
    });

    mongoose.model('users', usersSchema, 'users');