New to this section of MN I usually just spend hours reading through the AIBUs, such a thrill ha! but I just wanted to check what styles of dress are appropriate to be worn when invited to the evening-only of a wedding? It's my first time attending just the evening of a wedding and only my second time attending a friend's wedding (and in the first I was a bridesmaid so was told what to wear). There are a few people (one in particular) going to the wedding that I would like to impress? i don't know reconnect with that I haven't seen for over 3 years and probably won't see for another good few years so want to make sure I look good 
. Can MN act like my pretend big sister and help a girl out?
For reference the wedding is in September, I'm mid 20s, around 5'6 and just over 8 stone if that helps recommend dress styles.
P.S. yellow looks awful on me.