When logging in to Umbraco, you will be greated by the dashboard of the Content section. Similarly, if you browse to another section, you will see the dashboard of that section.
Which tabs and panels that are shown in a given dashboard is controlled by the /config/Dashboard.config
file. If you want to add or remove a tab (or just configure the various dashboards in general), you can do so here.
Eg. if you wish to replace the default Get started tab in the dashboard of the Content section, you can search the config file for something like (based on Umbraco 7.4-beta - the XML may differ a little from version to version):
<section alias="StartupDashboardSection">
<access>
<deny>translator</deny>
</access>
<areas>
<area>content</area>
</areas>
<tab caption="Get Started">
<access>
<grant>admin</grant>
</access>
<control showOnce="true" addPanel="true" panelCaption="">
views/dashboard/default/startupdashboardintro.html
</control>
</tab>
</section>
As an example, if you wish to replace the contents of the Get started tab, you can simply edit the path to the view of the control/panel:
<section alias="StartupDashboardSection">
<access>
<deny>translator</deny>
</access>
<areas>
<area>content</area>
</areas>
<tab caption="Get Started">
<access>
<grant>admin</grant>
</access>
<control showOnce="true" addPanel="true" panelCaption="">
~/App_Plugins/CustomDashboardPanel/Dashboard.html
</control>
</tab>
</section>