Is there a public bus that runs from opposite of the Guilin Railway station to Zhujiang Wharf ??

no, there is not public buses from the railway station to Zhujiang Wharf.
But i heard there are private mini buses from the Lingui Hotel (546 yards north to the station) to the wharf, which i do not suggest you to take.
If you travel with friends, i suggest that you take a taxi, it takes 40 - 60 minutes and costs CNY 90 - 100 per cab (remember to bargain with the driver).

HI,
Thank you. I will be alone,which is why I want the bus. Why would you suggest I don't take the private mini buses??

Because the mini buses are runned by private owners, so there are chances that they ask for a very high price and take you to somewhere else, instead of the Zhujiang Wharf. So I suggest that you use taxi out of your safety.

I have read that they are only 5-8 CNY....

yes, the price is about CNY 5 - 8. but like I said, there are chances that they ask for a higher price, which usually happens to foreign visitors. You can try to bargain with them if you can speak some simple Chinese.