Within the left side bar under ACCOUNTS, select Store. This will take you here:
Within the horizontal navigation bar, select Products. A drop down will appear. Select Inactive List. This will take you here:
Select the product that you wish to activate. A new page will appear that looks like this:
Select the Settings And Configurations tab. It will look like this:
Within the settings box next to Active, select the checkmark to the right to activate the product.