I need help with somthing huge?

I am working on a massive project called The Gods of Green Earth, it is a Western Sci-fi game Basicly I need somthing HUGE for a script.

What is this script you ask? Here is my elaboration I am working on my game as you know. And I am wanting to make an Inventory script where you can add attachments to said gun. And only being able to have 2 guns in your inventory. And a key you press to pick a gun up. And you drop the current gun you are holding.

Basicly I need a whole lesson on scripting as well... So I am kinda needing a master here... But yeah I need serious help here

Your pretty much asking for someone's life work lol. I don't know how to do this and it would be pretty cool but it would take like a day or 2 to make and figure out. Here's what I know

1. Make a GUI that is your inventory
2. Make the guns
3. Learn how to write if statements
4. Ask scripting helpers about any problems you run into.

This is a HUGE project and you would need to break it down into separate questions but basically u need to know how to write if statements, and how to write functions for mousebutton1down and stuff.

I wasn't that helpful (sorry) but this might be the only answer you get :p