Help with adding power ups to game

Hey guys im new to unity and i have a basic 2d space shooter game already made.. (The enemy's fall down at a random position and speed and the player shoots them etc.) The next step is my second scene or level... I want a box with a question to fall witch if the user grabs it before it goes of screen could give the user extra points or a shield of cover to protect him from the enemy's hitting him... so my question is how do i make a shield appear around the player...this shield will also have a health bar....

Any help will be appreciated(if u show code please use C sharp if that okays) I just looking for some logic or easy idea on how to go about this

Do it yourself and when you encounter a problem post the script here and ask a specific question. This isn't a place where you can just ask for code and expect someone to give it to you. Try this, make the "pickup" have a collider and put a script on it that uses OnTriggerEnter, which only works when a player moves into the trigger area, so you would have to set a send message function which works when the pickup moves into/collides with the pickup which sends a message to the pickup to activate and do whatever it is you want to the player.