EDIT: 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?
Yeah you can use any of the receiving addresses. The BTC will still end up in you wallet"Change addresses" are where your BTC balance is sent to in case you create a transaction that does not spend all the bitcoins in your wallet
For example if bob has 50 BTC in his wallet and wants to send Alice 0.5 BTC. A transaction will be created to spend all the 50 BTC but 49.5 BTC will go to Bob's change address while Alice receives are 0.5 BTC
source: coinguides.org
The Main reason for this feature in some wallets is just Privacy, so that it becomes a little hard for malicious people go track down exact amount of bitcoins you have received, the ones you have spent and your bitcoin balance