A Linux directory structure is not like Windows. The Linux structure is based on a very solid foundation rooted in UNIX history. Most user files will be located within the users home directory (in Linux parlance "~/") so it begins in a much tidier fashion. Modern Linux distributions now default to users having directories like: Pictures, Music, Documents, and Videos. It should be obvious what the intention of these directories. But you would be surprised how many people neglect these signposts.
But when we reach beyond the users home directory, things get a little less clear. There are often applications or application libraries that are on your system that shouldn't be (for one reason or another). For that task there is cruft-remover. When you find a directory or file you don't need you can remove them with the rm command. To help you find where files are located there is the locate command. Also when you are lost in the ever-growing list of issued commands there is the history command.
The Linux operating system contains so many helpful commands and applications. Some of these are obscure and some are quite obvious.