Creating a new Lookup Column
Lookup columns are reference columns in a table to represent a specific data from a related table (for example, the Projects table may need to contain the Client Company from the Clients table). When a reference column of Many-To-One cardinality is created, a lookup column is added to a table automatically.
The simplest way to add a lookup column to a related table is the following:
Click the Setup link in the top right corner of the window
Select a table you need.
From the setup menu select Column > Create a new lookup column.
In the References section click the Add Lookup button near a necessary relation:
The Lookup column form will be displayed: