I started seeing these weeds pop up in my lawn earlier this year. This is my first time having a lawn, so I didn't pay much attention to them, but now they're everywhere! My questions are: (i) what are they and (ii) how can I kill them without hurting my lawn? I put some Lilly Miller Weed N Feed on the lawn about 5 days ago...the lawn doesn't really look greener yet, but it looks like maybe some of the weeds are dying (not totally sure). How long should I wait before I can conclude whether that worked or didn't work? Should I try putting something else either on the lawn generally or just on the weeds? If so, how long do I need to wait? How long should I wait before I weed and feed again? I'm happy to buy whatever and do whatever it takes, but I don't want to fry my lawn either.

I'm a total noob, so any help is much appreciated! Thank you!! Here are links to the two photos:

http://i.imgur.com/C65gbH5.jpg

http://i.imgur.com/Y6ikmvr.jpg

Here is a link that might be useful: