1. Protest songs are the easiest of
the songs. Writing-wise, that is. I
think the most important thing is to
pick something bad to protest against.
No one wants to listen to a protest
song that protests something they like.
Some good things to write protest songs
about: nuclear war, the bad things that
people do to the environment, corrupt
politicians. 

2. Write the words. This is tough but
not too tough. You'll get through it.
Write down the reasons you hate the
thing you're protesting against. For
example: "The government is corrupt."
Get at least ten sentences like this.

3. Get a guitar.

4. Strum the guitar while saying the
sentences. Try to match the guitar 
playing to the saying a bit.

5. Find some people to sing your song
to, some people who probably really 
don't like the thing you're singing
about. Sing it to them like you're
really angry about the thing even
if you're not. These people will
respect you.