What is the name of the piano chord ? And how to play it on the guitar?

So it looks like you are playing a C-F-A, not a C chord, which would be C-E-G. Looks like an inverted F with the 5 being below root. On Guitar it would be a regular old first position F chord.

There is no conversion; A minor on a guitar is A minor on a piano. G major on a guitar is G major on a piano. The way to make any major chord on a piano is start with the note that is the name of the chord and play that note, then go up four half steps (counting all keys alike, black and white) and play that note, then go up three half steps and play that note. For a minor chord, first you go up three half steps from the note that is the name of the chord, then go up four half steps.

The notes are C F and A. The chord is F major