My business centers around the buying and reselling of goods, when trying to categorize my expenses I’m not sure where to put transactions of me purchasing my products

QBSE doesn't have any feature to track the inventory. You may have 2 options:

1. Migrate to QB Online Plus or Advanced.

https:// quickbooks.grsm.io/US

https:// quickbooks.grsm.io/us-promo

2. Utilize an inventory management app. But you have to migrate data (i.e expense transactions) manually to QBSE.

https://go.tradegecko.com/register?code=fiat-lux