how need make custom classification for my pic (size 64x64) of digits on CNN ?

[iam]

hi!
I have two questions:

1 .how need make custom classification for my pic (size 64x64) of digits on CNN ?

for example:

layer_defs = [];
layer_defs.push(......);

net = new convnetjs.Net();
net.makeLayers(layer_defs);

trainer = new convnetjs.SGDTrainer(net, {method:'adadelta', batch_size:20, l2_decay:0.001});

..... <- what need use for classiffication my picture (for example tag
<canvas id="mypic" width="48" height="48" ></canvas> )?

____________________________________________________

2.What is the difference between mnist_batch_0 and mnist_batch_20?
Both have 3000 monochrome image in each row?
_____________
thank you in advance