Select a service from https://ddosforhire.io/
then create an account and buy an premium plan next , install charles or traffic sniffer on your phone and start it and open your phone and sniff it's traffic , you will get the server address and everything , then take it and start and attack , if you still need help , then private message me , I will be glad to help you and buying ddos service from others can be expensive , so better do it yourself .