What happens when you try to connect the network? Do you get an error message? Does the app automatically detect the home network? You may also want to confirm that your specific Roomba is a WIFI connected model. Additionally I believe Roombas don't work on 5Ghz so make sure you connect to 2.4Ghz.
If you are unable to connect the app to your home WIFI it may be best to refer to iRobot’s website help pages for WIFI connection troubleshooting tips.