Can any one say the steps to complete.I first downloaded the sandits import file.then using data loader io i have imported the csv file from then Iam getting very much confuesed.and there is no field called last name in csv file.and which object should i choose to import the file.how many csv files should i create to import.shoul i divide account and contacts in different csv files.

The first challangeof this Superbadge seems to be problematic, showing the following message:
Challenge Not yet complete... here's what's wrong:
We could not find enough records in the 'Contacts' object. There should be at least 100 from the import.
What is interesting is that everything seems complete to me! I have inserted 100 contacts and 100 accounts, and of course all other items (Opportunities and Contact Hobbies).

Any idea why I see this error message?