The Lookup 
option opens a Lookup screen used to search for the values that you specify in the current text box on the current screen. Selecting an item from a Lookup screen list copies the appropriate value into the text box with which the Lookup command is associated (for example, a timesheet’s Default Project). To use the Lookup command and open the Lookup screen, click Lookup next to the text box or press F3.
Lookup screens are built on the console feature that is found in the System. The console feature provides for a consistent method to search for data and to save search criteria as "views" so that you can reuse the search criteria without re-entering the criteria every time that you perform a search. See also Consoles Overview.
Suppose that you have just opened Vendor Invoice and Adjustment under Financials | Payables, selected Type of Invoice and selected a Status of Pending. Now, you want to specify the vendor; however, you do not remember the vendor’s ID or the full vendor name.
Perform a lookup based on partial vendor name:
Click Lookup next to Vendor Name to open the Lookup screen for the vendor’s name. Vendor Lookup appears.
Specify the search criteria. In this example, type “long” in the Name column of the filter row. For more information about filter rows, see Consoles Overview.
Click Execute 
or press F5 on the Vendor Lookup toolbar to execute the search. The System searches all existing vendor names for those that begin with "long" (Long Building Supplies, Longfellow Painting, Longwell, and so on), and then lists the search results in the grid area of the screen.
Double-click the row that contains the vendor that you want. Or, select the row with a single-click, and then click OK.
Some screens use the Lookup command slightly different. Suppose that you have just opened Timesheet under Projects, selected a Status of Pending, and filled in all other required information in the header. Now, you want to add a line item to the Detail area; however, you do not remember the project ID.
Perform a lookup:
On the first line in the Detail area, click the Project ID cell, and then click Lookup. Project appears.
Specify the search criteria. In this example, type “S” in the Description column of the filter row, and then press Tab. The System searches all existing projects for those that begin with "s" (Sales Team Training, Support, Summer Conference, and so on), and then lists the search results in the grid area of the screen.
Note: If you want to save this search, right-click the column header and then click Save User Preferences. To clear any saved searches, click Clear User Preferences.
Double-click the row that contains the project that you want.
Note: When you select items in this manner the System remembers your most recently used selections. This list appears when you click the down arrow 
to the left of Lookup.
Using the Lookup feature to locate items in a lookup screen can be more efficient by following several guidelines.
Rearrange the columns in the order that is most useful to you. The columns can be rearranged left-to-right in any order that will make it easier for you to use them. To have a column switch locations with another column, click the down arrow to the right of the column name. This opens a list of all columns in Lookup. Select the column name with which the current column should trade locations.
You can also rearrange columns in Lookup by clicking and holding the column header and dragging the column to the desired location. Vertical arrows are displayed to indicate where the column will be located (dropped) after you release the mouse button.
Note: If you rearrange the columns in Lookup, the System automatically returns the columns to their original order when you close Lookup either by making a selection or by clicking the red X in the top, right corner of the screen. To make the current column order permanent, click Save View 
on the Lookup toolbar.
Use the most pertinent Filter Row columns. Type information in the Filter Row columns that are most likely to help you locate items quickly. For example, if you are looking for existing timesheets to approve, it may be more efficient to perform the lookup by status instead of by using other criteria. Looking up by status and last name may make the search even more efficient.
Provide as much lookup information as you can. Even with the Lookup feature, the resulting items list can still be long. The more specific you can be when specifying information in the Filter Row, the better. For example, if you are trying to locate timesheets where Joe Long is responsible, entering "lo" in the Responsible column of the Filter Row would list timesheets for Arnold Lo, Joe Long, Angie Lonce, Mark Lowe, and so on. Typing "lon" would narrow the lookup results even more.