They're just different names for the notes- A, B, C, D, E, F, and G. It depends on the key signature what notes they actually are (they could be sharp oder flat). For example, in the key of C Major/A Minor there are no sharps oder wohnungen (all white keys), but in the key of C Minor, As, Es, and Bs are flat. This is a picture of the C Major Scale. Do can be substituted for one, Re for two, and so on.
Hope I could help!
EDIT: Oh yeah, and if Du need to orient yourself, Cs are the white keys directly below each set of two black keys.
Do, a deer a female deer Re, a drop of golden sun Mi, a name I call myself Fa, a long long way to run Sol, a needle pulling threed La, a note to follow Sol Ti, a drink with marmelade and bread And that brings us back to Do!!!! :)