codelgniter login check help

[eluser]shivi[/eluser]
hi all i am new and I've been using recently codelgniter framework. so I'm not so expert .
my question is when i create form using helper("form") and after i made function in my home_controller

Code:

public function login(){
        $this->load->library("form_validation");
        $this->form_validation->set_rules("Username","username","required|aplha|xss_clean");
        $this->form_validation->set_rules("Password","password","required|xss_clean");
        
        if($this->form_validation->run() == false){
            $this->load->view("khalsahome_view");
        }else{
            $this->load->view("khalsahome_view");
        }
    }

so i want to know when user put username and password so how i can check inserted username and password is matches with database username and password and redirect user on home page with welcome message

if anybody can help me please thanks