Here are some visual tips on the way the interface works:

BatChmod allows you to change the privilege of a single file, of a folder and all its enclosed files and folders, or only the enclosed files and folders.

In order to change the privileges of an item, select the item and modify its privileges, then click the Apply button.

But one of BatChmod's strengths is the fact that it can affect specific privileges while retaining all the others. This allows you to do the following types of changes:

1. Changing the owner of a series of items while not affecting the group.
2. Changing the privileges of the owner or group of a series of files, without actually changing who is the owner or group, ie, giving write permissions to the group even if all the enclosed items belong to different groups.
3. Adding a specific privilege to all owners of files, without changing the owner itself (adding write access for example)
4. Removing specific privileges without affecting other privileges
5. etc.

There is also a menu item named "Clear Privileges" which clears out all ownership and privileges so you can select only the ones you want to add or remove.