You can very well transact your business through your website /internet . your liability to VAT or CST is the creation of law and the moment your turnover cross the threshold limit , you are liable for the CAT and CST registration under the WBVAT Act . Similarly the issue of CST will arise . The CST will arise only when there is a physical movement of goods in pursuant of sales .
Further you can claim the relief if any on the sales of the stationary item available to the dealer if any there .
We have an associate in Kolkata who can arrange your registration there .