To handle stock:
Go to the SALES MODULE ADMIN.
Create the warehouse if necessary. Go to Others -> Warehouses, and click Add.
Create the stock event if necessary. Go to Others -> Stock events, and click Add.
Create the warehouse stock, which relies on both a warehouse and stock event. Go to Others -> Warehouse stock, and click Add.
To see the stock you just created, go to PRODUCTS/ITEMS on the left navigation bar and press View under the Stock column for the respective item.
To handle price levels:
Go to PRODUCTS/ITEMS and press View under the Price column. Press the plus sign at the top right of the window to reveal a data entry form. Fill out the form and press save.