Unable to connect to internet via Wireless

From K-WiFi manager it shows that no AP , at times it shows Network ESSID , from the command
iwlist wlan0 scan , it shows wireless network
do i have to manage my configurations from yast, or any other network settings.

It depends–if it is a well supported chipset, then you probably will want to use KNetworkManager.

When you say “K-Wifi manager”, do you mean KNetworkManager? What chipset is it? Are you using wep or wpa?