Can not do games runs slow

Hello,
hi all i have a dell inspiron 537st and i cant seen to do the games on it it runs to slow i have been told i need a graphics download but witch one do i need a friend is going to do it for me via remote assistance but they need to no wat one i need there is so many on dell and i no nothing about computers do i need a chipset 1st or just down load the video one please help and explain like i am a 2 yr old lol thanks xx