Welcome to SS, Nathan.
Good first attempt too. A lot of newbs would be terrified to go anywhere near a OWC.
You've probably been told a lot already but I'll mention a few technicalities regardless.
Keep your action/description lines to a max of four lines. Break them up otherwise, and think in terms of 'shots' what your audience is seeing.
Get rid of your MOREs and CONT'Ds (in software) unless dialogue continues over the page. Some writers still use CONT'Ds but I think doing away with them enables a cleaner read.
Go easy on the exclamation marks - save them for moments of high crisis otherwise they lose their effectiveness. And stick to one (!). Using more than one looks hokey.
Ellipses - those three dots (each one is known as an ellipsis should be used sparingly too (three dots, not two or four btw) - they're used generally when a character's words trail off or that character loses his train of thought.
Ellipses should not be confused with the dash or double dash, (em dash, en dash) an em dash is just an elongated dash and can be formatted in Final Draft but it pretty much no longer exists in screenwriting anymore. Most people just type them as (-) or (--).
Example:
FRANKENSTEIN
Hey, stop swearing at me or I'll -
MABEL
What, what are you going to do, hit me?
Mabel just interrupted Frank and didn't allow him to finish.
Other things can interrupt dialogue too, for example: a crack of thunder, knock on the door, someone faints in front of a character etc. etc. In those instances the character's dialogue would end in that same dash, as it's interrupted.
Here's an example of an outside force interrupting the flow of dialogue:
FRANKENSTEIN
Mabel, you and I need to talk -
The telephone in the kitchen rings.
Frankenstein gets up, walks off.
MABEL
What, so you're going to get that when you just said we need to talk?
Do away with your CUT TOs - only time I would use them is maybe if you're cutting from a scene in Nigeria to a scene in AUSTRALIA, i.e., a big leap. Otherwise leave the directing to the Director.
Easy on your wrylies (parentheticals).
Be consistent with your scene headers/slugs:
EXT. PARKER’S BACKWOODS CABIN- DAY
EXT. PARKER'S BACKWOODS - CABIN - DAY
And, get yourself an online thesaurus - or a hard copy of one, like Roget's. It's an invaluable resource for a writer to have, i.e., make your verbs pop. Instead of using generic descriptors like: walks, looks, stares.
Ambiguity can be a killer too. Using your example:
Casey sits and watches the fire place burn...'That's actually getting your words mixed but you get what I mean.
It certainly added a little comedy.
I'll leave it at that. I'm sure others have covered info I haven't touched on. Other than this, read a lot (Pro and Amateur screenplays) and write a lot, and watch a lot of films. By the looks of it you'll catch on fast.
Two final tips: read your own work out loud, specifically the dialogue. And proof-read.
There's some nice imagery with this first attempt btw, and some of your dialogue is pretty good.