Chords: C, F, and G (G7)
The melody features the 7th of G, so a G7 chord isn't as important, but it does sound better during the verse.
Guitar Tutorial:Guitar Solo:Here's the
TAB for the guitar solo (http://www.guitartabmaker.com/2012/12/la-bamba-solo-tab.html)
Los Lobos's excellent cover from the 1987 film: