These are the instructions I followed. Connect the router to your computer using the enclosed ethernet cable. Open your browser and enter the address http://192.168.10.253 (check this to be sure). That should bring you to the router's green login screen. Enter the default ID(admin) and password(admin), and you will get the setup screen with blue tiles. Click on the tile labeled Repeater. You will get a screen showing the available wifi networks. Choose yours. It will then ask for the network login and password. Enter this, and, in theory, the router should be ready. I only got this to work once, and it crashes shortly thereafter.
That is exactly what I did. It sits up stairs in the middle of the house. Router is downstairs at one end of the house. I was having issues getting wifi upstairs to the opposite side of the house. Now I connect to this instead and have no issues having great wifi upstairs or downstairs. Can have issues if portable device is attached to upstairs(this device) and device is on opposite floor. This has not been an issue for my family of 5 or our devices. Works great!
You will need to login to the repeater to set up the repeater initially. After it is configured, it will function like any other wireless access point. How your devises connect it it varies, but you will generally have the access point and password saved on your devices, just like a router, etc
The actual coverage of any wi-fi antenna, or repeater, depends greatly on where it is placed and what is around it. I hate to be vague, but the signal from the Sabrent repeater is only a little less than standard routers I have tried, such as the Linksys WRT54, a very common wireless router. The outgoing signal is plenty strong on this repeater. The problem is that its receiver is almost worthless. Mine is setup less than 15 feet from my main router, with direct line-of-sight, and it does not pick up the main router's signal. When it does not receive the main signal, its repeated signal is blank. Strong signal, but no connection. I have stopped using it.