Objective:
To create a sub-folders in gmail account for maintain the favorite mails in our specified folders.
Step 1:
Login your gmail account.
Step 2:
Click label drop down box as mentioned below.

Figure 1: labels drop down box list.
Step 3:
Give the label name under label list. Like “personal” in Create a new label area.

Figure 2 : Label list
Step 4:
Now new label created and its visible in left panel under the inbox folder.