Practice and more practice. Everyone who plays the guitar has this problem at the begining, u keep practicing and u'll get it. First try switching between easy chords like say C to G and then to G7. Thats very basic. But the key word here is practice like it is with everything else guitar.
And by the way, this is the wrong forum for this. If u have any guitar related questions post them in the Beginners Q&A Forum. This forum is for Music discussion.
Overwhelmed as one would be, placed in my position
Such a heavy burden now to be the one
Born to bear and read you all the details of our ending
To write it down for all the world to see
But I forgot my pen, Shit the bed again...