uploading contact and account details in one action...how?

uploading contact and account details in one action...how?

Stupid question for sure...I uploaded an account list...then I uploaded a contact list separately. This was because there is no upload option which offers both account and contact fields for a single upload.  Did I miss an upload option that allows the upload of all contact and account information simultaneously or alternatively, how do I now connect my contact and account lists? Now when I look at my accounts, they have no contacts and vice versa. Thanks.