We've also tried to help you on other issues, but you don't always listen. We're trying to have you slow down a bit so you don't wreck your install. There's nothing like having to reinstall something numerous times. I say this in the worst sense, and not out of pleasure. For a program like this, which really is complicated, you don't want to spend a lot of time installing, patching, and hopefully recovering your hard work you had done previously.
We're also sorry if this seems to be too complicated, but unfortunately this is the case with a lot of things today. Why do TV remote controls have a gazillion buttons on them when all you want to do is change the channel and lower the volume? I dread the day when an elderly family friend gets a new TV or her remote's batteries decide they've had enough of it all and die. I get the call... This call is the kind that lasts for hours followed by a visit that lasts for hours to show her how to use the remote all over again.
Anyway, back to topic.
The reason for the open for edit in Explorer is this, and I apologize if this is too complicated. All of the Trainz assets, your downloads and built-in items, are not directly accessible by you. In the olden days with TRS2004 and prior, you could do that. You could find the asset and go in and edit for your heart's content. The problem with this model was every edit required deleting of program temporary files to make the program find the items you changed. The fact that you have to manually delete files in the program's folder meant that people would end up deleting the wrong stuff and have to reinstall, which can become a whole new nightmare unto its own. There was a third-party utility called Trainz Objectz that helped with the editing and this program did a find job, but due to many reasons it was never updated for the newer versions of Trainz.
So starting with TRS2006 and up, then Auran and now N3V Software, developed the Content Manager. Content Manager refers to everything downloaded by a location in a database. This single file, named Assets.tdx, keeps track of your content. The files for the individual items exist on your hard drive, but they are in a compressed form, meaning you cannot edit them directly. Content Manager allows you to see what they contain, and allows you to edit the content.
Editing in Explorer is fairly easy as Ed (Euphod) explained. I simply right-click on the item I wish to edit, choose Edit from Explorer, and voila! The asset's contents are visible in human form rather than in Trainz data form.
When done editing, I then close the Windows Explorer window, and then commit the item. Committing adds the changed item back to the database. This is the step that required deleting temporary files in the older version of Trainz. Today the committing takes care of this step and is a lot safer for your program.
If we seem like we're giving you a hard time, or are teasing you. take it in stride. Would you rather be among a bunch of grumps who don't bother to answer you because you're a newbie? I've seen that in many forums where the new guy gets the boot, literally for asking a question. As you've seen, you'll get the jousting and teasing here along with the information you need.
I hope I explained this well.
John