Cannot raise V-brake blocks high enough to align with wheel rim
You will find (usually an allen/hex key) bolt on the brake pad itself. Loosen that, align your brake pads then re-tigthen. You may also need to adjust again on the bars to get it to fit. 

You will also find it easier when loose and aligning them, to pull the brakes right up to the rim and tighten the bolts.

Everything you need to know you will find here: http://sheldonbrown.com/rim-brakes.html