First step:
Go to the business and use /biz > choose settings > choose restock > order components.
Second step:
After ordering components, you will receive a red marker where you have to go to rent a van (Benson/Boxville) and buy components from there.
Third step:
After arriving to the rental vans place, get in a van and rent it (/rentcar - it costs $5.000 to rent one). After renting a van, you will have to buy components (/buycomps).
Fourth step:
After buying components , go back to your business to sell the components (/sellcomps).
Notes:
(1) You must (be the owner of the business/have the key along with permission to restock) to be able to restock the business.
(2) The person doing the restocking process will pay 85% of the current component price and sells them for 100% of the components price to the business. This means there's a 15% profit for whoever restocking the business.