If you are planning on purchasing goods on accounts and managing the credit the vendor extends to you then you will need to create a vendor or supplier. The vendor in Dynamics AX is actually a role or a party. The party is first created in the global address book. Then a role of vendor is assigned to the party. The vendor record contains all the attributes or parameter you want to setup to manage the vendor in your systems.
In this walk through we set a vendor so you can see the basic process in action.