These are all the tutorial that we offer that deal with product options in eCart:
http://www.webassist.com/tutorials/Product-Options-with-eCart
http://www.webassist.com/tutorials/Add-static-product-options-eCommerce-Series
http://www.webassist.com/tutorials/Add-dynamic-product-options-I-eCommerce-Series
http://www.webassist.com/tutorials/Add-dynamic-product-options-II-eCommerce-Series