Uploading Inventory

We're trying to upload inventory levels in NOP Commerce and we can't find the place to do this.  We've tried downloading our catalog, but it crashes every time.  We only need to download a sku and quantity field then upload the file once we've updated the quantity.  What are we missing.  We are not IT people, but this seems like it should be something we should be able to do without paying an IT person to teach us.

Did you try reviewing the documentation on Importing? In version 4.3 you can try a test product of your choice export it to excel update the stock quantity and import it back, it updates the changes to product by sku number (the key element) if not found will create a new product.
Search the products you want to update check the tick box then export make your updates then re-import. Just do in small batches until you get comfortable it is working the way you expect. There are different ways to keep track of ones inventory in nopCommerce.
Also it would also help if you said what version of the platform your even using.

The only way is export / import products
(Unless there is a plugin that does it - check the marketplace)

So you are trying to export your products to excel and you get an error ?
Look in the Log to see if if gives you more info
What version are you using ?

Please share in detail with what exact you want and what error you having, so can get clear idea