You can create your own component by following way.
1.Create a component then declare and export component in module file like this :
components:{
shippingAddress:ShippingAddress,
promoCodes:PromoCodes,
paymentOption:PaymentOption
}
2. Use the selector of custom component in another component like this :
<shipping-address></shipping-address>
<promo-codes></promo-codes>
<payment-option></payment-option>