HYPER DOG!!!!! PLEASE HELP.....ITS A CORGI!!?

My grandma, Nana...has a Corgi, Joyce. Joyce is just now 1 year old. Well, I do 4-H and I already have a dog, Coco, she is a Sheltie. Coco is the champion of the dog shows, she LOVES agility and does great in obedience. I am going to show Joyce, and Coco in 4-H this year. Joyce already knows how to sit, but when she sits....she is sooo hyper that she shakes when she sits. Its an excited shake...her but just shakes...lol. (she stays sitting tho). I also cant get her to lay down or stay!! I have a choker chain, a regular collar, a 6ft leash, and treats...i also have a harness. They will start having dog meetings once a week at our fair grounds. That will be next month...which is March. I would like for her to know the basics first so she can win!! I just cant get her to do lay down, and stay. ( and STOP shaking) I know how to start her on agility, but she has to know all of this first. The fair is in 6 months. so i have a wile to work. She will also have to do showmanship. (if you have any tips, that would be GREAT!!). I have the collar from the 4-H meetings for that also. Thank you for the help! =D ps...im 13. this is my 3rd year of dog club in 4-H. I do know what im doing, i just cant get this dog to do what i want....so no rude comments please. =D She is a Pembroke Welsh corgi.