Hi there, I have only just sorted this out myself.
I have attached a work sheet below, roll over the heading titles and there is a little note outlining each point and what it does, this should help you sort it out.
To import this data do the following:
1./ Save this data sheet as a .CSV file and name it Products (or whatever you want). Make sure it is easy to recognise as you may end up with CSV’s for categories and attributes etc.
2./ Upload it either through the tools>import>upload option or via ftp (upload to admin>import folder)
3./ In tools>import>importation, s=first select what you want to import, in this case you are selecting products.
4./ Now select your Products.CSV (or whatever you named it)
5./ Leave “iso-8859-1 encoded file” unticked (not sure what it does but it works unticked).
6./ Change “Field separator: “ to comma ( , ) not including brackets or spaces.
7./ Leave “Multiple value separator:” as is.
8./ Click “Next Step”.
9./ At the top of the next page, you need to mark “Skip” as “1” in order to skip the titles line of the CSV.
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10./ Now in the table below, this is the break up of all your fields, check and make sure all the titles match the drop down options of that column (they should).
11./ Click the right arrow near the table to go to the last few entries which are the features fields. When you get to the first of the features field, click the drop list of that column and select “feature” from the drop list, this will open up a new text field in the drop list row, here you need to fill in what the title of that feature will appear as. In the case of the first feature, put here “Network” and the response for that will be as shown in the CSV for that column; “3G”, repeat this for all the other features or change as you need to for your specific features.
(image 3 shows this)
12./ Hit import.
13./ GO LOOK AT YOUR SIGHT AND ENJOY THE FACT THAT YOU DIDN’T HAVE TO ADD 5,000 ITEMS ONE BY ONE!!!
REMEMBER: You can not use the file attached here directly, you must save it as a CSV.
NOTE: You can also tick the “Delete all products before import ?” which will clear all products currently in your store, this good for the first import but remember not to tick this once your up and running otherwise it will reset quantities etc.
Enjoy…

Click thumbnail to see full-size image