Place the first block into the corner of your jig. If you don't have one, you can make a jig or buy one at an art supply store. A jig is a device usually made of two pieces of wood creating a perfect 90 degree angle. It will hold a woodblock in the correct position and allow you to place the paper on top of the block in the correct alignment for each run of the print. If you're making your own jig, make the wood block is flush with or slightly higher than the jig's interior edge and fit it squarely in the corner.
Bring the paper over the print block, lowering it slowly and, at the same time, bringing it to the raised edge of jig to align the paper. Some jigs may have dowels inserted instead of a higher outer wall of thin wood or cardboard. In either case the purpose is the same. When the paper is brought to the higher edge and it's square with the block you can lower it onto the inked block and it should be the perfect placement for each new addition of color.
Use your barren or wooden spoon to rub the back of the paper and transfer the ink from the woodblock. Lift the paper carefully when you're done and allow the print to dry before adding the next color. Continue to make prints of the first color until you have all that you plan to produce.
Repeat the process for the second block placing it in the jig corner, but this time place a piece of newsprint paper squarely over the block aligning it against the raised edges of the jib. Use the barren or spoon to rub the back of the paper and lift carefully when you're done. You'll see right away that the second color is where it should be and you can continue to print the rest of your run on good printing paper. If not, double-check the alignment of the block and use the newsprint again until the registration is correct.
Print the rest of the blocks in the same manner until you've completed all the prints you wish to produce.