From Delhi to Shanghai, one or two direct flights are available. You could take a flight to Shanghai first and then visit Zhangjiagang and Hangzhou. Since there are many fast trains running from Shanghai to Hangzhou, you could visit Hangzhou first. After that u may take a coach to Zhangjianggang as there is no railway station. Or, you can take a coach to Zhangjiagang first and then visit Hangzhou, which will be toilsome.