It depends on how your friend has set things up.
If he has simply created a machine user for your domain, then you will only have FTP and/or SSH access.
However, your friend can create a new WEBID (panel log-in) and give this WEBID certain panel privileges for your domain. This is done by going to Billing -> Account Privileges in the panel.
If you really want/need panel access, you could ask your friend to create such a WEBID for you. Of-course, the other option is to purchase a hosting plan for yourself.
Save [color=#CC0000]$50[/color] on DreamHost hosting using promo code [color=#CC0000]SAVEMONEY[/color] ( Click for promo code details )