First SNG: AK is obviously a good hand to push with. Depending on how short-stacked you were or how high the blinds were, you could also have just raised a good amount but you most likely were going down with this hand.

2nd SNG: You didn't say who started the raising but after being reraised once you should probably consider just calling. There's a good chance they have AA/KK(making them a huge favorite), another PP(making them a slight favorite), or AK. Edit: Ignore this, was thinking HU at table w/other players.

Even though these are the hands you went out on, there were probably some other key hands so it's hard to evaluate based soley on the info you've given.

Congrats on finishing ITM in 3 of 5, but that's pretty meaningless as to how you will do long term. If just starting you may want to read everything on this site and some of the recommended books as well. $100 is a bit low to be playing $10 SNGs, you might condsider playing $5(make sure it's a $5+.50) while you're getting your feet wet. At this point the experience should be more important then making money. There are also sites with SNGs under $5.

Good luck and welcome...