I'm sorry, but I didn't have the time to type up a complete tutorial just then
Well, SW said, the first step towards creating your own mod is to extract the ships, weapons, whatever from the mod it was originally from. The corresponding tbl entries should be your starting point, as they will tell you most of what you need to know about a given weapon or ship. Copy them to your own weapons/ships/whatever tbl. Then you need to look up what these entries are referencing. Laser weapons or beams for example refer to effects, ship or missile models need their textures extracted (unless they're using textures from retail or the mediavps, in which case you don't need to look them up). Then you need to find out whether those tbl entries are referencing entries from other tbls, such as armor.tbl, objecttypes.tbl, weapon_explosion.tbl, and others. This is where you'll probably need to keep the wiki's
tables page on speed dial.
During all this, you should use debug builds exclusively, and check and recheck with the debug build everytime you change something. If debug complains about something (and it will), fix it immediately. If you do not know how, the forum or the IRC channel should be your ports of call. If you do not do this, I can pretty much guarantee you that your mod will be an unplayable, buggy mess.
Once you have built your own mod out of bits and pieces from other mods (You should not try to simply reference a mod via the commandline options unless you really, REALLY know what you are doing), you can start FREDing, but be aware that the resulting mod will probably need some heavy balancing before it can be considered playable.
