Adobe air with flex, file new, open and save for Desktop software program

Question

I already have a headache from all the searching. I cannot believe this to be such a confusing topic as every software program we create must be able to save user input, right.
Here is the problem:
Novel writing software program Main window has tabnavigator with four navigatorcontent pages 1. characters, 2. worlds, 3. objects, 4. Editor
Each navigatorcontent page has user input fields in the form of textinput component, textarea component, richtexteditor component, etc.
problem 1:
The user needs to be able to open a new project and give it a name and state where it must be saved. All user input in the Novel writing software program must be attached to the file name the user specified - cannot give sample code cause I don't even know where to start looking anymore.
Problem 2:
If the user has now defined a new project name, all his input from the different input components has to be compiled into a single file that can be saved. (Dan Pichelman gave me a satisfactory answer on using the file.borwseforsave funtion.) That makes sense, but I first need to get all the user input into that single file. I was convinced that it must be an xml file and that there would be a guide on how to do this but...
Problem 3:
This brings me to another problem. All the pages I've researched so  far tell me how to load data from an xml file into a component, but not how to write the text from the component into the xml file. And this xml file cannot be the prefs file in the storage directory, it has to be named by the user and then after filling in all his text in the different tabs of the software, must be saved in this xml file and saved where the user chooses.
Problem 4:
now that the user put in his text and it is written to an xml file that he has named and set the path to, he goes on vacation and in two weeks opens his saved file to work on his project again. All the data that was stored in the xml must now be written back into the different user input components so he can continue working on his project, truth be told, there are some samles and tutorials on this subject, but again from only a single page perspective not a multiple tab perspective.
Problem 5:
Now the user has deleted and/or changed some text he put in when he started, he wrote some more text in the textareas and texteditor and he clicks the file - save button. The xml file or whatever needs to be used must be updated and saved with all the changes overwriting the old file.
Problem 6:
The data entered by the user will end up being a book of say 400 pages. This data will obviously be mostly in the richtexteditor component, so whatever method of saving is used, database or xml or whatever, needs to be able to contain all this data.
Thought, if you are working with for instance, microsoft powerpoint, it has multiple pages all containing different user inputs and when you click flie - save, it saves all that input into one file. When I as a user opens that saved file it loads all that content back into its place and I can change and manipulate the input and save it again. I would have thought this would be one of the first things adobe or any other software would teach as this is what sofware programs are all about. But alas, the tutorials on this subject for adobe air for Desktop application is extreeeeemely rare.
My promise is, if someone can help me with this or there is a tutorial out there that covers this properly I  will write a tutorial on this for other newbies as I progress step by step.  
Pleeeeeeease help this ignorant novice
Regards

Answer 1

to save a file you would do something like:
FileWriter fw = new FileWriter( fileName );
textComponent.write( fw );
fw.close();See the JFileChoose API for filtering files by extension. The API gives an example.