Problem in Reading ID3v2.3 tag?

Question

I have a problem in reading an ID3v2.3 tag. First of all I read about id3 tags from www.id3.org. The documentation of id3 tags says it has first 3 bytes which contain 'ID3' then 2 bytes contain version and revision number(for example 03 00) & then next first byte contain flags(Unsynchronisation, Extended header, Experimental indicator) then next 4 bytes is reserverd for size. I am able to read size. But My problem is that when I seek my pointer from current position to forward direction (size which I have taken from ID3 tag size), so it means I have reaached at the end of ID3 tag, It means so next byte we will read is the MP3 data byte, but it is not case. So Help me in detecting MP3 header & MP3 data with the help of ID3 tag size.  And My second question is that Is MP3 frames are mixed with ID3 frames or Is it completely seprate from ID3 tag. If it is seprate from ID3 tag so in the end of ID3 tag there is a first MP3 frame. Is is right or not? Tell me