I looked at the "receive" tab, but didn't see anything labeled "address". However, if I look at addresses, I see a list of perhaps 20 "receiving" addresses (the word highlighted in green) followed by a list of perhaps 10 "change" addresses (the word highlighted in yellow). Should I use any one of those "receiving" addresses?
The "Receive" tab in Electrum is used for generating invoices that you can send to other people if you want them to pay you specific amounts of bitcoin or if you want them to pay you within a specific time frame. Most people do not use this function at all.
You are correct in saying you should use one of the addresses marked as "receiving" under the addresses tab. Right click on the first address which has no previous transactions (you can tell by the number 0 in the far right column), and use that as your receiving address. Alternatively, from the second "Filter" drop down at the top, select "Unused" and use the first receiving address. It is good practice to use a different receiving address every time you receive coins to your wallet, as it is good for your privacy.
After you have pasted your receiving address from your clipboard, double check that it is still the same. There exists malware which will change addresses stored in your clipboard in an attempt to steal your coins. Always double check your addresses before confirming any transaction.