Your pinyin doesn't match what you want to say at all. "zai zhong"(在中?) doesn't make sense. That should be "zai zhongguo"(在中國) "wo men" (我們) means "we" not "I". The "men"(們) makes it plural, so you should change that to simply "wo"(我) "de"(的), the possessive particle has no use in this sentence, so you can delete that. hen(很) alone just means "very", "hen duo" 很多(meaning "a lot") is what you're looking for. (zai zhongguo, wo you henduo pengyou)在中國，我有很多朋友 OR (wo zai zhongguo you henduo pengyou)我在中國有很多朋友

wo2 zai4 zhong1 guo2 you3 hen3 duo1 peng2 you3 ：）

zai zhong guo wo you hen duo pengyou. I means wo, have means you, many means xuduo,friends means pengyou,in china means zai zhong guo,so it should be wo you hen duo peng you zai zhong guo,but we aways put "zai zhong guo" before a sentence,so it should be "zai zhong guo, wo you hen duo pengyou",and I just mean wo.we means wo men.

Wo jiao le hen duo zhong guo peng you. 我交了很多中国朋友