Connecting SAP R/3 to website

Hello Gurus,

I have a requirement to connect my Web Portal directly to my SAP R/3. It is an eCommerce site in which the customer places an order and chooses a billing plan and I want it to reflect in my SAP R/3 system. I am new to this cross integration and I have no Idea how this is done. Any help with on this would be greatly appreciated.

Hoping to get your expert advice on this as it is an urgent requirement.

-Thank you,

Pavani