After browsing about the problem, I get solution to solve this problem:
- Fist you must turn on network interface
tnto@slackware#ifconfig wlan0 up
- Assign essid value
tnto@slackware#iwconfig wlan0 essid "Merpati 24"
- Request IP Address from DHCP Server
tnto@slackware#dhcpd wlan0