There are two types of APs LWAPP and Autonomous
If you need to integrate that to the WLC you need to convert it to LWAPP
To verify, you need a console cable and access the CLI through Console
Default creds is : Cisco/Cisco --capital C
IF:
<mac-address>: -LWAPP
ap: -autonomous
Check the cisco documentation about converting Autonomous to AP (google will do the trick)
With regards to joining your AP.
I would recommend that you assign your APs statistically, there are many ways you can do this
1. Create a DHCP Pool and once the APs join assign them
2. Invoke through CLI
Since those are just 3 APs I would suggest invoking it in the CLI, here is how to do it:
#capwap ap ip address <IP> <NETMASK>
#capwap ap ip default-gateway <IP>
#capwap ap ip controller ip address <WLC-IP>
#show capwap ip config -to verify
If you want video tutorials, check this youtube result: https://www.youtube.com/results?search_query=adding+APs+to+WLC+cisco
