How do I use UserDetailsService properly? Where do I define it exactly?

@Configuration
@EnableWebSecurity
public class SecurityConfig {

    @Bean
    public SecurityFilterChain securityFilterChain(HttpSecurity http) throws Exception {
        http
            .authorizeHttpRequests((authorize) -> authorize
                .requestMatchers("/login").permitAll()
                .anyRequest().authenticated()
            );

        return http.build();
    }

    @Bean
    public AuthenticationManager authenticationManager(
            UserDetailsService userDetailsService,
            PasswordEncoder passwordEncoder) {
        DaoAuthenticationProvider authenticationProvider = new DaoAuthenticationProvider();
        authenticationProvider.setUserDetailsService(userDetailsService);
        authenticationProvider.setPasswordEncoder(passwordEncoder);

        return new ProviderManager(authenticationProvider);
    }

    @Bean
    public UserDetailsService userDetailsService() {
        UserDetails userDetails = User.withDefaultPasswordEncoder()
            .username("user")
            .password("password")
            .roles("USER")
            .build();

        return new InMemoryUserDetailsManager(userDetails);
    }

    @Bean
    public PasswordEncoder passwordEncoder() {
        return PasswordEncoderFactories.createDelegatingPasswordEncoder();
    }

}