There are many aspects of Fallout modding. First and foremost, you should decide what you're interested in - if you want to tweak Fallout or Fallout 2 (that's a huge difference actually), like adding/replacing art or adding extra weapons/items, you'll need to learn other skills than if you want to add a new quest or a new area entirely.
Assuming you want to create a new area with new characters (like you said - a new char with some items, some dialogue in a new shack), I'd start playing with the Mapper first. In the Mapper package there is a PDF from F2 devs explaining
some of the things of how it works.
As you learn to build maps in the mapper, I'd suggest you design your mod thoroughly - start very small - like a single character in a single house built on an existing map. When you know exactly what the house should look like, what the character will have to say, write the character's dialogue. I advise you against using any dialogue editors.
Then check out the
Fallout Modification FAQ. Although a lot of info found there is outdated, there's still plenty of valuable knowledge on prototype building, graphics editing and scripting.
With that, you should be able to build your shack on an existing F2 map, build a new NPC prototype and place it there, adding some items and stuff. Then grab a copy of FSE (Fallout Script Editor), read all available scripting tutorials, take a look through the original F2 scripts and try your hand at it.
Sounds easy, but it's not. Anyway, good luck with your project and remember that design is key - without design you'll have difficulty getting anywhere at all. Also what Killap said. If you have difficulty finding answers to your questions, ask them here.
Go to the tutorial page and read through the threads, stuff like this takes time. Anyone who made anything worthwhile for Fallout did it the hard way, persistence and patience. 
