premixed combustion using Zimout model
 

HI,
I am a newer in premixed combustion. When I use the FLUENT to modeling, I am confusing about the premixed combustion using Zimout model in FLUENT. I can't find where can I specify the mixture(methane-air) equivalence ratio or about the mixture materials.
Anyone knows how to solve it ? Please help me. Thanks in advance! This question is confusing me several days!
Best regards!