The form is the way the song is laid out. Here is the song form for "Sweet Home Alabama" in it's most basic form.

"Sweet Home Alabama"
- Lynard Skynard

Intro
Verse 1
Interlude Riff
Verse 2
Chorus
Solo 1
Verse 3
Chorus
Solo 2
Verse 4
Chorus (2x)
Outro - Piano Solo

The chords are the same for each verse, and each chorus with some slight variation here and there. I go about this actually writing out a chord chart with repeat signs, key signatures, etc. If you put the song structure down on paper, it really helps to make the song less intimidating and I have seen even professionals go about this using merely notebook paper some times.

Even if you simply are playing for fun (which we all are in some way), having a basic idea of song form will make leaning and eventually writing songs much more enjoyable.

Good luck and hopefully this answered your question.... :confused: