Newbie Mission Building questions

I'm starting to take baby steps in terms of making a mission and have a few questions:
1) where do you save the missions to? The editor saves as .fs2 files, but I haven't found a folder with many of those in it (i.e. the "missions" folder where I would assume you would save to). I know the game saves to a folder in my docs and there is a sub folder (cache) there which looks like it has mission and/or game info, but they are not .fs2 files. So I am somewhat confused
2) once I figure out where to save it, how do I play it, to see if it works. Thanks.

My install path is the default. Wouldn't there already be a mission folder? If there isn't where are the missions for the main campaign stored? When I start messing with things I generally copy all the imporatant variable folders (missions, saves, etc.) and put copies somewhere safe so I can simply restore them if (when) I screw something up.

My single missions folder is empty, not even the WC3 missions. Once I create the missions folder like you said what is the path for where I should place it so any missions I create appear there?

OK, finally figured out the path. It's C:\Documents and Settings\your name\My Documents\Volition\Wing Commander Saga\data\missions in case anyone else was having a problem finding it as well. Now I just have to write a mission worth playing. I'm sure I'll be back with more questions but thanks.

Have been trying to make mission, but having problems as they fail when I try to test run them on fred. So I took on of the game missions and loaded it into fred and changed 1 thing (ship) just to see if it would work and it crashed as well. This is the error message:

Oops hit send too fast here it is:
Couldn't open mission 'M0J1-BG-Hermes.fs2'

<no module>! KiFastSystemCallRet
<no module>! WaitForSingleObject + 18 bytes
<no module>! <no symbol>
<no module>! <no symbol>
<no module>! <no symbol>

What am I doing wrong?

when I create a mission folder and put the WC4 files in it, the game crashes if I want to select the campaign. is it not playable ?