could someone please explain to me how to make a rose bud and a leaf.I'm new at this or can you tell ? thanks in advance.

Hope this helps.

http://www.wilton.com/decorating/basic/index.cfm

It has a list of different icing types (i.e. buttercream, royal icing, fondant, etc) and techniques that you can use with each.

Good luck and welcome to CC!