Hi Rosie9591 - What problem, specifically, is she having with each of those elements? What kind of game has she decided to create for the project?
Has she read through the GameMaker Guide on our site? http://www.sciencebuddies.org/science-fair-projects/project_ideas/Games_GameMaker_Guide.shtml?from=AAE
The links to additional sources and references may be helpful.
Sounds can be created using an external application (or finding free or royalty-free sources for sound effects or using the sounds that come with GameMaker) and then adding them into the game. Here is some additional information on sounds from the GameMaker site: http://wiki.yoyogames.com/index.php/Sound
As for the players... can you offer additional information regarding what she is trying to do?