How do you bar all 6 strings?
It is possible to hold down all six strings of the guitar by using a full or partial barre (holding down two or more strings with one finger- usually the index finger) and pressing the other remaining strings with the non-barring fingers.
Is there a trick to barre chords?
A quick (and cheap) trick to make your guitar easier to play is to detune the strings. This will lower the tension on the strings and make them easier to push down. You can tune down a half-step, but the effect is not dramatic. Tuning down a full whole step will work on most guitars, and chords will get much easier.