"Create new workspace" window has some parameters that can be confusing for new users, so we will break them down for you. You can change all these parameters later down the road so it is not crucial to get all these names right on the first try.
Mod display name
Mod display name is the name of the mod as it will be shown in the Mods list or in any other place where displaying the name of the mod is relevant to the user. This name should be user-friendly, but should not contain version numbers as there is a version number parameter for this that can be changed once the workspace is created in the workspace settings.
Minecraft version
Select the target Minecraft version you want to develop your mod for. You can switch this version anytime, but keep in mind that switching between eg. Forge and Data pack workspace type will not be possible later. It is recommended to keep this at the selected version as this version is the most supported version for the given MCreator version.
Mod ID / namespace
Mod ID (also known as modid) is the machine name of your mod used by the forge to identify your mod. It should only contain English lowercase letters and should be unique for each mod. We suggest you do a quick research before selecting your modid so you do not collide with any existing mods.
For data pack or similar mod types, Mod ID represents the namespace of the given plugin.
Mod Java package name
This field is used by a Java code generator. All mod source code will be placed inside this Java package. MCreator fills out this field with the appropriate value for you, but you can change it. Try to follow this pattern for package names: tld.domain.modid. If you use a custom package name, make sure it is a valid Java package name.
Workspace folder
The workspace folder is the root folder in which the MCreator workspace will be created. This folder is the self-contained folder with all data about your workspace. You can change the location of this folder at any time. Deleting this folder means deleting this given MCreator workspace.