First time building an enclosure.

[Wizwise2000]

Hey everyone.
I have wood to spare and figured I'd use it to built a small "test" enclosure. If it works, then I'll use it, if it fails, oh well. I have a few questions. First how do you all install the tracks for the sliding glass? Put the glass in and then install? Also, what should I use to seal the wood? And how long should I leave it so it can air-out? Do I leave it outside to air-out, in the house etc?
Sorry if I sound completely stupid, I just don't want to use it for a future animal and have him/her injured. Last, do I seal all the wood, then put it together then silicone? In that order?

Thanks so much everyone.
Shane