I caot see my devices in my second router

I bought an ADSL Modem router mistakenly because my ISP's modem router is vdsl so instead I want to extend it and make that as my main access point. The reason my ISP's router does not have parental controls at all. However, even I have successfully done it, I could not see my devices in my new router but instead it appears in my ISP's router. I decided to make both DHCP server on and manually set their IP addresses. How do I make my second router to be the main access point so that my ISP's router will be my modem? I want all my coected devices in the second router so that I can manage them and do some parental controls. Please let me know if there is something that I have missed or mistake that I did. Thanks in advance.