I'm sure you've seen these all over bloggy world, right? These are totally doable by the average person with CS5, so here we go!
For each grandchild's name, you're going to make a new layer. This will enable you to edit each child's name separately, without affecting all the other children's names. Also make a separate layer for each birthdate. Here's how I make all those separate layers. Type the kid's name, then click over on the right side of the screen where it says, "Layer 1." It should change to the kid's name (or whatever text you just typed). Double click on your white box (AKA the poster) and type in the next kid's name. Keep repeating until your done. Next do all the birthdates in the same manner (feel free to change the color if you want). You don't even need to really type all of this information in the exact spots that you want it to be in in the end, because we'll adjust all that later.
To make the text go up and down instead of left to right, make sure the correct name is highlighted in your list of layers (right side of the screen), and then highlight it on your grandparent poster. Click "Window," and then "character" so that a new box pops up. There should be a little drop down menu you can pull down in the upper right hand of the box. The first two options in this drop down menu are important for changing the direction of the text. Click "change text orientation" to make the text go up and down. You want to make sure that "standard vertical roman alignment" in unchecked. I'm still trying to figure out how to get the up and down layers to flip flop and face the other way. I did it once by clicking "image" and then "image rotation" but it doesn't seem to be working for me now, probably because the text is not an image. Another thing you could do is right click the "T" for text in the leftside bar. Four options will come up, and the second option is the one that makes the text go up and down.
Once you have the name going up and down, go ahead and do it to the birthdates you want to go up and down as well.
You can click an image and drag it to a new location by clicking on the layer name, and then clicking on the appropriate text on your poster. Move the mouse around the name until you see the cursor with the little arrow cross. Now you can move it. Once it's in its new location, click the checkmark at the top of the screen.
If you need to stretch out a word or a birthdate so that they are the same length, click on the image layer name on the right side of your screen, and then hit "Ctrl T." You can now drag it to make it longer or shorter. Click the checkmark when you're finished.