Head into the Animator Window, and set up 2 states, "Open" & "Close". right click on "Open" state and click "Make transition" drag that to the "Close" State.
We'll revisit that transition in a moment, but first, we need to create a Parameter. On the left side of the Animator window, there's a tab called "Parameters", click on this, and at the top (Next to the search field) there's a small "+" icon. Click on this and select Bool from the dropdown. Rename this bool to "Boo_Open".
Now, click on your transition you set up before (click the line, not the state), and look to the inspector panel. Underneath the animation timeline is a section called "Conditions". Click on the little "+" Icon here and select your bool, and set the value to False. Now, when that bool is "False" it will transition from the "Open" state to the "Close state". You can set this bool to change from an FSM on a game object through the "Set Animator Bool" Action.
On your game object you'll also want to setup a bool value, again, we'll call it "boo_Open" (for consistency). When you click on the door, you want to fire off a "Bool Flip" Action, then a "Set Animator Bool". Set up the actions parameters so the Animator bool uses the bool value of your FSM variable. Now you'll see that when you click on the door, it changes your bool value in the game object and the Animator, and transitions to the "Close" state.
From here, you want to make a transition from the "Close" state back to the "Open" state, and set the condition to Boo_Open = True. Now, assuming this is set up properly, clicking the door should switch between the open and closed states in the animator window... Finally you need to select the animations you want to play on each state and drop them into the "Motion" section in the Inspector Panel on the relevant state (Click the state, not the transition).
In regards to your additional question:
When you import your animation file to unity, Click on it in the "Project Panel", and over in the "Inspector Panel" you have 3 tabs. Select the "Animation Tab" and you'll see a section called "Clips". At the bottom of this section is a little "+" icon. You can click this, and set start and end frames for an animation.