question about web store taxes

hi. Just in US for about 2 months. have a question about open a store on the web such as ebay store.

I live in NC. Which state tax should I collect? Say I import something from China. Then have a storage in NC, or other state, if there is one much better than NC. sell the staff on ebay to North America. Tax wise is the store same as a local NC store? Please give me some advice on what should I do, or what should I avoid.

Thanks a lot.

LaoPZ