I am pretty new to this stuff but I have been learning a lot about it, from what I've learned you find a product from something like aliexpress or ebay and put it on your site and when someone orders something you go to that site and order it to their address. If this is correct what happens when your getting thousands of orders and you can't possibly fill out all the information? Are there any apps or ways to automate this process? Any help would be appreciated, thanks.
Find one apps in Shopify store but it charge USD 29/ mo, I think up to now still unavailable, because when I try search about similar software or apps to tackle this problem, I realized this transfer data from Aliexpress to Shopify become a online job, you can found some gigantic companies hire some freelancers to transfer the information manually. I suggest you try DhGate, in cases you find similar products that you intend to sell in there, since DhGatee have api that integrated with Shopify, which help you save some times.