Dell N1100-ON Reference Manual page 774

Configuration of the bridge priority is given preference over configuration of
the root primary or root secondary configuration, which is given preference
over the configuration of DirectLink Rapid Convergence.
Example
This example configures a switch to be the spanning tree root bridge for
VLANs 12, 13, 24, 25, and 26. This presumes other switches in the network
utilize the default bridge priority configuration.
console(config)#spanning-tree vlan 12,13,24-26 priority 8192
774
Layer 2 Switching Commands