Loading Data From a Data Target in sap bw

Can you please guide me for carrying out his activity with some important steps?

I am having few request with the without data mart status. How can I use only them & create a export datasource?

Can you please tell me how my data mechanism will work after the loading?

Follow these steps:

1. Select Source data target( in u r case X) , in the context menu click on Create Export Datasources.
DataSource ( InfoSource) with name 8(name of datatarget) will be generated.

2. In Modelling menu click on Source Systems, Select the logical Source System of your BW server, in the context menu click on Replicate DataSource.

3. In the DataModelling click on Infosources and search for infosource 8(name of datatarget). If not found in the search refresh it. Still not find then from DataModelling click on Infosources, in right side window again select Infosources, in the context menu click on insert Lost Nodes.
Now search you will definately found.

4. No goto Receiving DataTargets ( in your case Y1,Y2,Y3) create update rules.
In the next screen select Infocube radio button and enter name of Source Datatarget (in u r case X). click Next screen Button ( Shift F7), here select Addition radio button, then select Source keyfield radio button and map the keyfields form Source cube to target cube.

5. In the DataModelling click on Infosources select infoSource which u replicated earlier and create infopackage to load data..