Don't Know what I'm doing

Okay so i bought a router to help improve my wifi and a wifi extender but before i got to the extender i wanted to set the router up and get the nighthawk app set up as well. I have turned off myc wifi disconnected it and all, i have done the same to the router and nothing. The app is not working for me and is constantly asking me to sign in, i believe that i have signed in over 200 times in the last 2 hours. I need HELP someone please walk me through the set up process. it is annoying me and like the subtitle says i have no idea what im doing, i just want to improve the wifi. Please and Thank You!!