Does your router even have the function you want. Very inexpensive routers do not have any ability to filter traffic. Since you know the mac and the ip address if the router has the feature you just fill the screens in that do that function. Exactly how varies a lot from router to router.
Not being able to see things like dhcp allocations and active ip and mac is again a issue with inexpensive routers. Many routers are designed for people who just want a box they can turn on it somehow magically works for them. They do care to learn anything about the box and want to pay as little as possible. Route manufacture have been reducing features on lower end devices to keep the costs down, less calls to customer support from people...