If Camrivox CTI for Salesforce has been enabled it should appear as a small panel (click on this link for the user guide) in the left hand margin of your browser window, once you have logged into Salesforce.
If you would like to make changes to the softphone please see the following Salesforce guides.
https://emea.salesforce.com/help/doc/user_ed.jsp?section=Personal_Setup&loc=help&target=cti_personalsettings.htm
https://emea.salesforce.com/help/doc/user_ed.jsp?section=cti_admin&loc=help&target=cti_admin_phonelayoutscreate.htm