Now I have Acer Aspire 5733 and it has Intel HD Graphics (Core i3) card. I've been searching for changing this card into a Nvidia or another graphics card. I've seen "mxm" or other port things and I don't think that I can change it. Can anyone help me about it? Can I change it? And, if it's possible, which graphics cards are compatible with it? ANYTHING which is better is possible for me.
Most mainstream laptops, such as your Aspire, feature onboard graphics (in older models on the mainboard and often nowadays, built into the CPU) without any provision for upgrading the card. Some high-end gaming laptops have separate graphics cards using an MXM slot, but a laptop in the class of yours wouldn't have such a thing.
I'm sorry to say the only way to get a better GPU is to buy/build a new computer.