In AdWords advertising you put several keywords. When someone searches Google with any of those keywords, the advertisement shows up in the Google search page. Is that correct ? Can I use the keywords like - Google, Yahoo, eBay, PayPal etc. ? Thanks.
Correct. No, you enter keywords or phrases one at a time. This is so that you can bid on each keyword a different price. You can't bid on a string of words separated by commas.