Select the file, click the three dots → Move to, and pick the destination library. Unlike dragging files through Windows Explorer, this keeps the full version history and metadata intact.
Go to Library settings → Versioning settings and enable version history. Every time a file is saved, SharePoint keeps a snapshot of the previous version — you can view, restore, or delete any of them.
From the site home, click + New → Document library, give it a name, and it's ready to use. Add columns for metadata, configure versioning, or start uploading straight away.