n00b ram install

Hey guyz im not too savvy when it comes to computers but i recently purchased a 512mb ddr stick of ram from circuit city installed it and my computer wont boot i think i got the sequence right afew times after i got the sequence right it would come up with a hardware changes menue and asked me how i wanted to boot my computer was i supposta boot it in safe mode? Now it wont even come up with that option when i boot my computer with the ram stick in any help would be appreciated.