Industries records are associated with Account records through the lookup field Industry on the account form.  They are a handy way to filter lists of accounts or contacts (through a related table).  Industry is a required field on the account record.  There are two ways to create an industry record. 

The first way is to navigate to the Configure area of TekStack and select Industries under the  Sales section of the Sitemap.  

From there you will click on the + in the grid to create a new industry record.

You can also create an industry directly from the account form, click in the Industry field and select the + New Industry to open the form to create a new Industry.