would i be right in saying it is the degree of the major scale ?
It's the degree of which ever scale is being played.
C D E F G A B C , = 4th right ?
1 then what about when people play harmonic minor scales with raised 4ths etc , which scale are these '4ths' relevant to , the 4th of a major scale again ?
Yes, essentially. If a scale is referred to as having a 'diminished 5th' then it means it is the major (or minor) scale with a flattened 5th instead of the usual 5th. People normally quantify this by saying which scale it refers to however, for example "It's a major scale with a flattened 7th"
when i see music in notation form , i see that there are often sharps and flats written on near the time signature , and apparently you can find out the key of the piece ? , then what if there are none there ? if there is no sharps or flats near the time signatures is it c major because this scale has no sharps or flats ?
That's the key signature of the piece. Every key has a 'signature'. C major and A minor have no sharps and no flats, hence no key signature. (Every major key has a 'relative' minor which shares its key signature; A minor is the relative minor of C major, they are basically the same scale with different tonic (1st) note.)
If you play a 'C' major or 'A' minor scale, you'll notice there are no accidentals: C,D,E,F,G,A,B hence nothing to note in the key signature. If you look at the D major scale, it has 2 sharps: D,E,F#,G,A,B,C# so it's key signature has 2 sharps - F# and C#. Looking at the key signature tells you which accidentals to play, so if the key signature has an F# in it, you know that any F notated must be played as F# unless it is preceeded by a natural symbol.
If you didn't do this you'd have to write out every accidental which would be messy, and the only way to find out which key a piece was in would be to analyse the harmony, and that wouldn't always give the correct answer!
3i never know which sharp or flat it is! , they always seem to hover over a couple of lines due to their size
Basically the centre of the symbol will intersect the line or space it is affecting. To notate Bb you would put the round bit of the flat symbol on the B line of the stave.
There is a tonne
of music theory to be learnt, but you've got to start somewhere!