If you create standard WebPart-pages located in document libraries your problem will be, that the resulting pages will not have the common quicklaunch menu and users will start complaining about it.
The internet provides a lot of solutions involving SP-Designer oder fumbling with the SharePoint controls in ASPX code.
The easy way is to copy one of the existing sites (default.aspx for example) into a document library, optionally rename it, and then use „edit site“ and place your webparts wherever you like. And you have the quicklaunch menu included automatically.
To copy a default site you dont even have to use SP-designer. Simply type
http://your_top_site/your_path_to_sitecollection/_layouts/sitemanager.aspx
and use this tool to copy a default site into a document library.
Happy customizing