Do you already have other APs configured? It should basically be copy/paste from one of those, changing s/n and model.
Otherwise, you need to define a service-profile to define SSID, auth, encryption, and the associated VLAN. Then a radio profile linked to that, which can define channels, power levels, etc. Then the AP (or auto), linked to the radio-profile.
For a basic config, using WPA2-PSK, something like (I think I've got this all right):
set service-profile MySP ssid-name MySSID set service-profile MySP auth-fallthru last-resort set service-profile MySP psk-phrase PassPhrase set service-profile MySP rsn-ie cipher-ccmp enable set service-profile MySP rsn-ie auth-psk enable set service-profile MySP rsn-ie enable set service-profile MySP attr vlan-name MyVLAN
set radio-profile default service-profile MySP
set ap auto mode enable set ap auto time-out 10 (radio-profile default is default)
Check the docs for how an AP finds its controller. L2 broadcast, then DHCP option, then looks for DNS name "trpz," or something like that. There isn't much config on an AP - it could have static IP and/or mesh SSID configured and/or WLC address, not much else. The rest it gets from the controller when they talk. If your's has a WLC controller configured, you might need to connect it to the same subnet/VLAN/broadcast domain as the controller you want to use to get it to come up, then do "clear ap X boot-config" from the WLC cli.
