Read the description for installation instructions!
Unzip the file and place the Explorer folder into your Mount&Blade Warband/Modules folder. For steam users, this should be in your Steam/Steamapps/common/ folder.
/.../Mount&Blade Warband/Modules/Explore/WSE Lua/WSELoader
Everything is set up to work with Steam. All you have to do is load the mod from the WSELoader.
I recommend making a shortcut to place on the desktop (or wherever.) You CAN still play the mod without WSE, but there will be more bugs, more crashes, and over time less compatibility with the mod. Regular launcher is officially unsupported for Explorer, but for now it still mostly works.
Here's a forum thread that should more than calm your nerves, with 190 pages of proof that this isn't anything harmful:
-You can still see the (textureless) overland map for a moment when starting/reloading games
-Sometimes your character bugs if you open the Party window while camping
-You might see Script Error messages when going between scenes
-Some towns are still using the Native scenes
I am sure I'll forget someone right now, but I want to give a special thanks to:
RRaptor, luigi, Pope, James