how do i divide my canvas into 3 without using guides?

Several ways to do this. One way would be to open all three images and put them all into one document. Make sure they are cropped to the same size. Then change the canvas size by 300%

Then you can use the move tool to position them.

You can also use guides and change your unit measurement to percent and use 33.3333% and 66.6666%

Guides can be very useful and they are easily available.

Open a file.

Choose View and checkmark Rulers. It will put rulers alongside the left and top of the Applications Frame.

To get a guide, click in a ruler and drag into your image.

To move a guide choose the Move tool, straddle the line and drag it

To hide guides, Cmd+H and to show them again, key Cmd+H again.

To get rid of guide, use the Move tool. straddle the line and drag it back whence it came (I like the old word "whence")

Try it.

So I just found out that you have to install the guideguide to actually get the guides, but isn't there a way to do this without having to buy guideguide?