This will save a file named “export_all_products.csv” under the var/export/ directory for your Magento installation. The export success screen will look like this and will specify the file name where the products were exported.
Using an FTP client download this file to your local computer. The file will include columns for each of the attributes you have defined for your products. Open it in a spreadsheet program (MS Excel, Open Office Spreadsheet) and add the products you would like to import. Make sure you are copy/pasting the corresponding attributes in the correct columns. Also here is when you will have to add the category IDs. Use the IDs from the text file you saved earlier and put the corresponding category ID for the products you are adding.
Once you have accomplished the above go back to the Magento administrator area and choose System -> Import/Export -> Dataflow - Profiles -> Import All Products. Then choose Upload file and browse for the .csv file that you have updated with the products that need to be imported. Once you have uploaded it click Import All Products again, then Run Profile, select the .csv file you have just uploaded from the drop down menu and click Run Profile in Popup. A status screen will open and the products will start importing
When the import completes you will get an export success message.
You can now go to the products section of the Magento administrator backend and check the imported products. They will be present there and assigned to the corresponding categories with the attributes you have added for them.
