How to put Granny Squares Together
Start by laying out the granny squares in the pattern you have sleceted right side up. There isn't a right way or wrong way to pattern them. However, most crocheters agree that the corners should be the same color.

Usually the border around the granny square afghan is the same color as the corner squares. It can be, however, what ever color you want it to be. Just try to make sure that it's one of the colors in your squares.

The same goes for the yarn that attaches the pieces together.

Different people have different ways of attaching granny squares together. Please remember, this is how I do it. You might find a way that is easier or prettier for you. This is a guide and not the end all be all of grannies.

Once you have your pieces all laid out and arraigned, pick up the top corner square and the one next to it in the same row.

Place the squares together with the right sides facing each other.

Locate the middle chain stitch of the top corner.

Stick your needle through that chain and attach the yarn.

Crochet the two pieces together making sure that you are matching them together.

Once you get down to the next corner, make you last stitch the one in the first chain stitch of the corner.

Pick up the next two squares in the columun.

Place them together with the right sides facing each other. Find the middle chain of the corner of the both the new squares.

Stick your needle in all four middle of the corner chains.

Now proceed to crochet down the new two squares.  And keep doing this until you have no more squares left in the two columuns.

Crochet in the middle chain of the corners of the last two squares. Now finish off (FO).

Now you have floppy columuns. Repeat the same process going across in rows.

When I get to the  corners, I chain 2 and skip the corner and continue crocheting right down the row.  That makes the piece look more professional and neat.

Let's talks about the border. You do need to crochet around the whole afghan to finish it off. I usually do a double crochet and at the corners, I crochet three times. That gives my corners a neat point. If it's a little girl's blanket and I have enough yarn, I will do a shell stitch on top of the double crochet. The shell is my favorite border stitch. You might like the puff stitch or picots better. Experiment and try. Just stick with one thing on the whole piece.