Install Pi hole and have a lot of questions

I have pi4 2gb and i try to install pi hole.
I want to have 3 projects on my pi.

  1. Pi hole
  2. Security cam viewer
  3. NAS

I am not sure if is possible to have all in one pi, but for now i just want to use pi hole, and think about other things later.

I watch a lot of tutorials and go to install pi hole.
I want pi hole on smart tv and tablet.

Now is the part when i am confused, i think when i install that i choose google dns.
So for now i must go to tablet and choose dns settings and type 8.8.8.8 and 8.8.4.4 right?
I dont find this option so i download app DNSChanger for IPv4/IPv6.
But ads are still here, and also on hole nothings shows, 0 numbers?
Also on menu i dont see whitelist and block list page?
And where to find some good blacklist to add?

Thank you, i am new on this and i have so many things i want to learn, my english is not perfect so maybe thats a reason i dont find answer i understand.

Not right. The network clients use Pi-hole for DNS, and Pi-hole in turn uses Google DNS.

Ok, what i need to do next?

Oh i see i just need to type to dns settings ip adress of my pi on devices i want to black and thats all?

Perhaps.

Please refer to Pi-hole's documentation on Getting Started, particularly the sections on Prerequisites and Making your network take advantage of Pi-hole

Now suddenly happens when i want to go admin page of pi hole, i get this message: '403 - Forbidden.
Advices?

What is the exact URL you are using to visit the admin page?