MS-DOS (and Windows) uses a hierarchical file structure like Unix. In MS-DOS files are identified by a drive (C:, A:, etc.), followed by a path that identifies directories (folders) and finally a file name itself. An example of a complete file name is A:asmproject1example.asm. The symbol is used as the separator between path components and as the name of the root (top-level) directory. Most MS-DOS systems are set up to display the current drive and path as part of the prompt (e.g., C:WINDOWS>).
Default refers to the drive or directory that is used if you don't specify a drive or directory in a path. To change the default (current) drive, simply type the new drive letter and a colon.
To change the default (current) directory, use the CD command. The symbol .. is shorthand for the parent of the current directory. For example, if the current directory is WINDOWSDesktop, then CD .. will change the current directory to WINDOWS. (Note: MS-DOS is not case-sensitive – cd works just as well.)
The MD command creates a new directory. To create a new directory in the current directory, use MD directoryName.
The DIR command displays a directory of files in the current folder. Alternatively, you can give the path of the directory in which you want, like DIR C:projects. You can use * as a wildcard character. For example DIR s*.* finds all file names beginning with the letter s.
The COPY command copies a file from one directory to another. The format is COPY source destination. If you don't specify a name for the destination file, then the name of the original file will be used. You can use the COPY command to create a duplicate of a file in the same directory, but with a different name. The COPY command allows use of the wildcard character * to copy a group of files.
The EDIT command is used to create or modify a text file. EDIT filename invokes a simple text editor opening filename if it exists or creating it if it doesn't. EDIT has its own help system with more information than you need about this editor.
The REN command is used to rename files. Its format is REN oldName new Name.
The DOSKEY command loads an extension to the command processor that allows you to use the up-arrow key to recall a previous command, which then can be executed again or edited.
You can get more information about most commands by typing command /?
Just because you are doing some work in MS-DOS doesn't mean that you can't use other Windows tools. It is fine to use My Computer or Explorer to create directories, copy files, rename files, etc. You can use Notepad to edit files, but be careful since Notepad likes to put a TXT extension on every file name. (You can end up with crazy names like program.asm.txt.) In general you should avoid using a word processor to edit text files such as assembly language source code files.