for this thing you have use the routes in ci which are as given
Consider the small example
$route['aboutus'] = "any controller is map to that name";
samplesite.com/aboutus [aboutus is controller] samplesite.com/contactus [contactus is controller]
$route['memberaccount/(:num)'] = "any controller is map to that name/$1";
samplesite.com/memberaccount/32
if still not getting try the above link https://www.codeigniter.com/userguide2/general/routing.html