Where can I print the giveaway poster, and what size is it?

Download the poster from https://www.tendso.com/100-pages-giveaway. The current PDF is A4 portrait, or 210 × 297 mm. You can take the PDF to any print shop and ask for A4 printing. Ask the shop how much printing costs. Hang the poster where customers can see it. Then take the required photo before applying.