Computers have either integrated graphics (on motherboard) or dedicated graphic cards. Dedicated graphic cards give you more flexibility and innevitably a better result (in graphics).
Generally, you cannot upgrade a laptop (like a PC) with any old third party graphic card. Some laptops allow an optional extra dedicated graphic card, normally integrated at time of purchase. This is what you want. This will be more expensive, the dedicated graphic card will have dedicated RAM and better processor.
So, initially start looking for a laptop which does not share it's onboard RAM with video, normally indicating it has a dedicated video, or ultimately an Nvidea graphic processor, this way you get a good graphic card.
Without myself looking now (I'm a bit busy) I cannot recommend one, besides, laptops come and go every month.