You can access Web Mapper to map source schema elements to target schema elements.
To access Data Mapper:
Go to ACCOUNTS and click Manage Objects.
Expand MAPPINGS and click Mapping > CREATE Mapping. The Create New Mapping screen is displayed in a new page.
- Type the name and description of the new mapping activity in the Name and Description text boxes.
- Select the Project from drop-down list of Select Project.
- Click Create to open the Select Schema window.
Select the Source and Destination Layout checkbox which you want to use for Mapping and click Load.
Info You can select multiple source and multiple layout for mapping. 
Click Modify Settings on the Create New Mapping screen to expand the advanced properties of the new Mapping activity.Anchor Modify Settings Modify Settings 
Select the Splitting Data checkbox to enable the splitting of data.
Info If you select this checkbox, then you have to split the data. You can do this by setting the Splitter XPath in the Data Mapper .
- Enter the number of records into which you want to split the data, in the Split Number of Records field. For example, if you have a source file of 100,000 records and you want split this file into records of 10,000 each, then you need to enter 10,000 in this field.
- Select the Parallel Processing checkbox to parallel process these records. By default, records are processed sequentially.
Enter the number of chunks you want to process concurrently, in the Maximum Concurrent Processes field. By default, value of 1 is entered.
Info It is advised to change this value, if Parallel Processing is selected. Else, only one chunk is processed at a time and hence sequentially. Click Create to open the Select Layout window.
Next Step
Load Source and Destination Layout