This is done under "Products".
1) You can add a new product with the "quick add" option, where you just add a few simple details such as product name and base selling price.
You can also add a product and continue to input more details.
2) The details for products run deep! It is recommended to add a product with as many details as possible, rather than doing a quick add. In order to continue, your product must have at least one vendor assigned to it.
There are also special features you should consider when adding new products:
General- choose an SKU number for the product, add a tag to the product to help identify it, specify a tax class, place minimum and maximum order quantities, product descriptions, set a default vendor and price markups, and add weight and dimension specifications.
Files- upload an image for your product
Category- allocate your product to a category
Variants- add variations to your products such as size, color etc. The set up of your variants is done under the Admin menu item
Units of Measure- define how products are packaged, as single units, packs of 4, or a case with 2 packs
Vendors- assign a vendor to the product and indicate certain details such as minimum/maximum quantities and cost price
Inventory- see a summary of where your stock is, how many items there are reserved and how many items are available. Additionally, you can update stock and add it to various warehouses
Pricing- manage selling price by determining variant pricing and bulk discounts, and manage cost by determining vendor pricing. You can also set pricing various rules with different conditions
Everything is managed by you and you can customize fields to your specific needs.