You need to bridge the wireless interface and the Switch Virtual Interface( SVI). This is done by configuring each with a bridge group number the same as a Bridge Virtual Interface (BVI) number.
Since the wireless express configuration has assigned bridge group number 1 already, you just need to create BVI 1 and then configure InterfaceVlan 1 for bridge group 1.
Using the SDM is probably easiest. Click Configure, Interfaces and Connections, Edit Interface Connections. Click to highlight Vlan 1, click Edit and select the Connection tab. Click the drop down for Configure and select VLAN for IRB to change from VLAN for Routing. Enter 1 for Create new Bridge Group and enter IP address and mask ofInterface Vlan1 (172.20.8.49 and 255.255.255.240). Click the NAT tab and configure for Inside. Click OK to apply. Click Yes to continue when advised that the same IP address as Vlan1 is being used.