First of all, you need to enter in a partnership with steam. You can do this via their steamworks page: Steamworks.
Then you have to use download SteamWorks SDK and use a program in it to upload the files. I don’t exactly know how that works as I don’t have the 100$, but there exists an official tutorial: Steamworks Tutorial #1 - Building Your Content in Steampipe - YouTube, And there is the official documentation: Uploading to Steam (Steamworks Documentation).
For windows, you will want to build to a zip from GDevelop and upload the extracted folder, not the zip itself or the installer.
If you want to add achievements, I have made a guide (it is a very outdated and not very good but should be an OK starting point?): Steam API Guide