Let me try.Your firend's family name may be ‘于’or '余'or'俞'，it's ，and his(her) name may be '寒' '汉' '撼'，so you can combine the family names with the names.

I don't mean to be a party pooper, but what you provide is not enough, because Mandarin is a tonal language and we need the tones if you really want to get the job done right. But still, please take a look at this table first: http://www.quickmandarin.com/chinesepinyintable/ Just left-click on the intended combination and another small window will pop up. In it are the four tones for the very same combination. Left-click again on any of them to hear it said in different tones (the one on top is in the first tone). My wild guess is that since your friend is a girl, yu is in third and han is in second. And another friendly pointer: yu is in the lower-right corner of the table.

each chinese character has 4 tunes ,firstly, you should know the tune of YU and HAN ,then you can pronounce it verywell. the pronounciation of Chinese is very easy.