Pravit, do you see those slash-chords like Dm/f? It means they should be played like this: first play bass string with your thumb so that it gives 'f (Fa)' then play chord Dm with your index,middle and ring fingers, plucking three treble strings simultaneously. For performing that press down the fourth string with your ring finger on the third fret (that is 'fa'), then play Dm as usually with your index, middle and pinkie.
Try this chord - Am/E - you should know where which notes are on the guitar fretboard. E means 'mi' and so 6-th string open would give you 'E'.
Pravit, it's difficult to explain without illustrations. Contact me , I've played the guitar for 13 years, and I think I can help you.