ABAP Proxy Import Structure

ok. Guys and gals I have limited ABAP expierence and have a simple question around loops. I have an ABAP proxy setup that receives an XML file and stores the contents in the INPUT method. The two structures under Item I am working with are I_HEADER and I_ITEM.

I can access the values in I_HEADER with something like the following:

CLEAR w_header.

w_header-guid = v_header_guid.

w_header-description = input-I_HEADER-DESCRIPTION.

w_header-process_type = input-I_HEADER-PROCESS_TYPE.

w_header-posting_date = sy-datum.

now I currently have been testing the proxy with the following for my i_item structure. This is hard coded but I would like to import from the INPUT structure.

CLEAR w_item.

w_item-guid = v_item_guid.

w_item-parent = v_header_guid.

w_item-product = '00000000000000000000000000000000'.

w_item-description = 'Test Item Description'.

APPEND w_item TO i_item.

How would I setup my loop to read the I_ITEM-ITEM table and populate with the imported values instead of hard coded. For instance using this example I would need the values from I_ITEM-ITEM-DESCRIPTION and I_ITEM-ITEM-PRODUCT?

Thank You.