How to attach a model to a mount?

[tdrsmynm]

Like the title says, I want to try to attach a separate model to a mount/flying mount, to be specific the model below (I found it on xgm), to a hippogryph. However, I barely know anything in modelling, and I dont really see any tutorials here. But still, I want to know how.

 

[Hermit]

I dont really see any tutorials here. But still, I want to know how.

Tutorials