Do you mean that you are getting a login screen asking for your user name and password? If so, that's standard procedure.
If that's what you mean and you don't want to enter it each time do the following:
1. Open the System Preferences and Open the Security and Privacy pane.
2. Unlock the pane if necessary and select the General tab.
3. If Disable Automatic Login is checked, uncheck it.
Note that if you choose this setting anyone who boots your computer gets logged into that account.