When you are a silver 3 and someone needs you to play a platiunm 5 ranked for him......

My boyfriend is in China right now so he said he want me to play a ranked game for him so his rank at platinum 5 won't drop mean while I'm a silver 3 I was very scared to play a game against platinum, gold, and diamond so I decided to go support.What happen was they ban Sona and Soraka which was the only 2 supports I know how to play. I use Teemo to support sometimes but i don't want to risk the chance that we will lose.Then I saw Leona and use her for the first time. Leona is a very good choice for being a support and she is very easy to use.She has high damage and she is tanky too.