Import Vendors & Associated Contacts in One CSV Upload

Import Vendors & Associated Contacts in One CSV Upload

I am a new user and would like to import about 300 vendors as well as the people associated with those vendors as contacts. 

I can set up a CSV file to; Vendor Name, Contact Name, Telephone etc. 

My question is how can I import them so the contacts are imported to contacts and the company they work for is imported to Vendors?

My first attempt was unsuccessful so I also need a helping hand deleting all the existing records and starting over again. 

Thanks in advance for your help.