To me it is very unclear what it really is you want. Perhaps it is easier to elaborate at little bit more. I can interpret your question in many ways:
Do you wish to put this as your title screen background?
In the System tab in the Database you can change the background, to do that you should first add this image to the folder in which the others are.
Do you wish to have this picture show at a certain moment?
You can make an event based on when you want it to show and use the 'Show Picture' command. Again, to do this you should add this picture to the folder used in this event.
To get a faster and/or better answer it is much easier for anyone if you explain your question more.
'Product Discussion and Support' is for when you have queries about Resource Packs and dlc in general.
Please specify if you want to use this as a picture or as a parallax. If you want to use it as a picture, you will need a plugin that both fixes it to the map so that it doesn't move with the player and also allows you to set the z value so that it shows behind the sprites, not on top of them. Your alternative is to use this as a parallax map. As I don't use MV I'm not sure if you still need a plugin to lock it in place so that it doesn't scroll with the player.
As much as I have followed the parallax conversation, putting ! in front of the file name makes it lock on place automatically. Also need to make sure the picture is exactly the same size as the game map, ie game map tile sizex48 on both sides.
To set it as the background, you'll need to add an exclamation mark to the start of the filename (e.g. !Background.png) so that it will stay in place, copy the file to "Pictures", and then just set it as a Parallax background.
You might run into trouble though, as your map is very big and doesn't seem like it would fit precisely with the tiles in RPGmaker. So you may need to alter the size. Assuming you're using RPGMaker MV, a tile is 48x48 pixels, so you'll want your map's dimensions to be divisible by that.
I make a lot of custom parallax for my game project and what has been said I will verify through headache and buggy experiences.
Make your parallax same size as map or it will loop or be cut of prematurely compared to map view (black areas.) make your map divisible by 48 in dimensions (So lets say 1296 x 672) That's a map of 27 wide by 14 tall. if you make it 1300 then it will be shifted 4 pixels more than the foreground. That may not matter unless the tile images on it need to line up with the ones on the map.
You can use Yanfly's regional restrictions plugin if you don't want to put down any "map stuff" but want a walkable and impassable area defined on top of the parallax. The regions are all set using the 1-255 color tiles in the map tabs.
If your map needs to scroll, make sure the sides line up and blend to allow for that. One way i check for that is I take my map file ( While in an editor and swap the right side for the left side so that the middle of the image is where the left and right side would meet at a loop point. Then I can smooth out any conflicts with my eraser or pen. Trust me, even slight anomalies can be seen when that background starts scrolling.
Hope you get it sorted out for yourself. I thin it is a great map enhancer using them.