You already know how to create a DHCP scope, so I will skip that. Users are placed into ip address ranges by VLAN. You create the VLANs in Configuration> Network> VLANs. Create a VLAN Number. In Configuration> Network> IP, you can define the range for that VLAN. After that you go to the Virtual AP profile and change the VLAN number to whatever range you want your users to end up in (Configuration> Wireless> AP Configuration..Edit the AP-Group that your access points are a part of. Expand Wireless Vlan> Expand Virtual AP and click on the Virtual AP for your wireless Lan. Edit the VLAN Number there).
You can give access points a static ip address but it is normally unadvised, due to the overhead of managing statically addressed devices. To change it to static, go to configuration> Wireless Lan> AP Installation. On the provisioning screen, you can select an access point and give it a static ip address and then reprovision it.