How to create custom object and custom field in Salesforce?

Prerequisites:

A Salesforce account in a sandbox Performance, Unlimited, or Enterprise Edition organization, or an account in a Developer organization.

For more information about creating a sandbox organization, see “Sandbox Overview” in the Salesforce online help. To sign up for a free Developer organization, see the Developer Edition Environment Sign Up Page.

In this step, you create a custom object called Book with one custom field called Price.

1. Log into your sandbox or Developer organization.
2. From Setup, click Create | Objects and click New Custom Object.
3. Enter Book for the label.
4. Enter Books for the plural label.
5. Click Save.

  You've now created your first custom object. Now let's create a custom field.

6. In the Custom Fields & Relationships section of the Book detail page, click New.
7. Select Number for the data type and click Next.
8. Enter Price for the field label.
9. Enter 16 in the length text box.
10. Enter 2 in the decimal places text box, and click Next.
11. Click Next to accept the default values for field-level security.
12. Click Save.