Windows 7, as well as Windows 8, lets you chose whom to share your files and folders with. If you do not want to share one of your folders and want to make it Private, or if you want to share it with only select people, you can do so as follows:
Make a file or folder Private
Right click on the folder, select Share with and then choose Nobody. To choose select people, select the Specific people option. From the File Sharing box which opens, you can choose the users.
Windows 7 will offer the Homegroup option, whereas you will not see it in Windows 8.
Once you make the file or folder private, a padlock overlay icon will appear.
Hope that helps!