new to blender

hey all I just downloaded blender and trying to get the hang of the controls. However when I try some of the shortcut keys to use blender some work some don’t did I do anything wrong when I DLed it? (for example when I try to modify the size of a cone to make it more angular and narrow I can highlight the whole thing but when i hit A to edit it I can’t manipulate the edges of the cone like the larger end)

You add an Object and it’s in Edit mode by default, with all Verts selected. To edit the Mesh you stay in edit mode and select (hotkeys RMB, B, BB, Ctrl-LMB) only those verts you want to manipulate. If some verts are selected and you hit A it will deselect All and none will be selected to manipulate.
To edit the Object you hit Tab to goto Object mode.