I will not repeat the advice already given by the other members.
Once you are in contact with potential dropshippers you need to also discuss with them in what format they will supply their products feed (images, descriptions, prices, etc.) to you, as you would then need to upload all of those products to your own ecommerce website. You need to ensure that the ecommerce platform that you will choose allows you to easily/automatically upload the products.
Hope this helps