At first glance I thought this was an idiom for the proverbial "grain of salt" often heard in English, which of course refers to one’s skepticism. It might be said that one should take anything posted by SR, without attribution, with a grain of salt.

But upon reading the following:

Siempre he considerado las criticas como mi mayor motivacion para seguir escribiendo y poniendo mi granito de arena por el bien del beisbol.

which I found on a forum for the "Acereros" of Monclavo, Coahuila, Mexico.  The "Acereros" (which I suppose would translate to "Steelers", as in the Pittsburg Steelers) are a professional baseball team from Coahuila.

I think now that "granito de arena" would be the equivalent of the American idiom "two cents worth".

SR, who wishes he understood Spanish better, which, according to his wife, is the perfect language for speaking to God.

I wasn’t able to find "granito de arena" anywhere on line.

But I found a nice list of Spanish Idioms:

[url=http://www.noborders.net/spanish/idioms.html]How Real People Talk
Dictionaries are great, but real people use idioms

[/url]

Idiom: Por un pelito de rana

Literal: By a little hair of the frog

English: It was a close shave.

Sitran

I finally found it:

     (British) (informal) (= role)
we must all do our bit    todos debemos aportar nuestro granito de arena

"Poner mi granito de arena" seems to be used too!

Doing my (small) part (for the good of baseball!).

Sitran

Let me reply you, since my first language is spanish.

"Poner mi granito de arena" would be "to contribute a little in a big cause"
let’s see this example:
"Doné 5 dólares para la colecta de los niños etíopes. Quise poner mi granito de arena".

Thanks, MBP.  I understand perfectly now!

-Tim