Hii,
I’m an absolute beginner with unity, and I managed to get some simple stuff done via youtube videos, etc. But I’m having trouble finding out how I can add my own characters into my game, and my own enemies, etc. And I have designed them in photoshop, but I don’t really understand how I can make sure it will actually act like a character, pls help so I can move on with programming everything 
Advice #1: Don’t start a thread with the subject “plz help!”. It makes you look whiney and nobody wants to help the whiner… Not to mention it tells the readers nothing more than the obvious… Anyway…
There are some things you have to decide on:
-2D or 3D? (How is the player going to move?)
-What’s the camera angle? (3rd, 2nd, or 1st person view?)
-Do you want the animations to dictate movement or do you want the animations to run while movement is controlled separately?
Something to keep in mind is that when you’re programming something, you have to build everything. You want the enemy to take 2 steps, pause, aim, take another step forward, then FIRE! Well, you’ll have to program all that in. There are ways to do it more efficiently than others.
I’m still a noob but what has helped me a lot is letting go of that ‘dream game’ just a bit in-order to learn the tools-at-hand. What I mean is I created ‘draft’ projects that are for learning purposes. You’ll come to realize that there is a lot more than “hey i drew some characters”. Something I never thought about and never really WANTED to learn is UI. As it turns out, UI is crucial to learn if you want to make decent games(eg. healthbars, bulletcount, playernames, tooltips ‘press E’, HUD etc.).
You’re the man for downloading Unity and opening it up, though. Keep grinding and keep learning. Don’t be too choosy about what you’re learning. It all comes together and you’ll realize you’ve saved time if you keep your ears open.
Good luck.