Notes written beside the board
Two questions come up so often, and take so long to answer properly, that answering them next to the export button would be rude. Both are about the gap between a board on a screen and a thing on a wall: how many pictures will genuinely fit, and what has to be true of the file before a printer will make a good job of it. Neither is a tour of the buttons. The buttons are on the board and they are labelled.
Both were written against the same tool you are using, with the same numbers the size panel shows, so nothing in them is aspirational. Where a piece says a setting exists, it exists.
A hundred photographs on one board
Where the number of pictures and the size of the paper argue with each other, and who should win.
Counts from fifty upward, cell sizes worked out against real paper sizes, what a gutter costs you at each step, and the width in millimetres below which a face on a wall stops being a particular person. Read it before you decide how big to print, not after.
Answers: How small is too small?
Getting a board printed
The arithmetic between a pixel count and a sheet of paper, and the file a print shop actually wants.
Dots per inch as a relationship rather than a property, the standard sizes written out as pixels, bleed and margins on a board that draws neither, and the honest comparison between sending a very large PNG and a high-quality JPEG. Read it before you export, because two of its decisions are board settings.
Answers: What do I send them?
What is deliberately not written here
There is no piece on choosing a layout, and there will not be one, because this board ships no layouts to choose between — the arrangement is the work, and a note telling you which of our templates to pick would be a note about a product we decided not to build. There is nothing on adding captions or headings either: no text tool exists here, so a guide to using one would be a guide to a button that is not on the screen.
What is missing and probably should not be: a note on scanning a shoebox of prints well enough to put on a board, and one on colour, which is the subject everything above carefully steps around. Both are real and neither is written yet.
Back to the board
Reading either piece is optional. An empty board at twelve by eighteen inches opens in a second and will tell you more in five minutes than a page of prose will, and the grid generator will show you what a hundred cells look like faster than the arithmetic will.