So I suppose your router is connected to internet, which means it can provide internet, what needed is you Pi to ask for an IP address using dhcp discovery message, I'm not experienced about wifi_config so I suggest you to turn it back to default.
Then check interfaces manual by man interfaces, there you'll find many settings for setting the interface settings which are located at /etc/network/interfaces. After that edit the text file interfaces by sudo nano /etc/network/interfaces. Add there a stanza including the details of your router(it's SSID and if exists passphrase. And example I can give to you is :
allow-hotplug wlan0
auto wlan0
iface wlan0 inet dhcp
wpa-ssid "SSID"
wpa-psk "PASSWORD"
If you turn all the other settings to default, this will work for sure. You can get all the meanings of the lines above from man interfaces and also from another answer that I provided : How to setting up wlan0 that automatically turn on when eth0 is switched off?