Define a tab to display the data stored in your custom object records.

1. From Setup, enter Tabs in the Quick Find box, then select Tabs.
2. Click New in the Custom Object Tabs related list.
3. Select the custom object to display in the custom tab. If you have not already created the custom object, click create a new custom object now and follow the instructions in Create a Custom Object.The label of the new tab is the same as the plural version of the custom object label.
4. Click the Tab Style lookup icon to display the Tab Style Selector.

   If a tab style is already in use, a number enclosed in brackets [] appears next to the tab style name. Hover your mouse over the style name to view the tabs that use the style. Click Hide styles which are used on other tabsto filter this list.

5. Click a tab style to select the color scheme and icon for the custom tab.

   Optionally, click Create your own style on the Tab Style Selector dialog to create a custom tab style if your org has access to the Documents tab. To create your own tab style:

   1. Click the Color lookup icon to display the color selection dialog and click a color to select it.
   2. Click Insert an Image, select the document folder, and select the image you want to use.

      Alternatively, click Search in Documents, enter a search term, and click Go! to find a document file name that includes your search term.

   3. Select a file and click OK. The New Custom Tab wizard reappears.

6. Optionally, choose a custom link to use as the introductory splash page when users initially click the tab.
7. Enter a description of the tab, if desired, and click Next.
8. Choose the user profiles for which the new custom tab will be available.

   For Professional Edition users and Salesforce Platform One license users, tab visibility is set to Default On.

9. Specify the custom apps that should include the new tab.
10. Select Append tab to users’ existing personal customizations to add the tab to your users’ customized display settings if they have customized their personal display.
11. Click Save.

This blog is very useful to learn about tab creation in salesforce.