See Add an image in Pages on Mac - Apple Support
It could be as simple as dragging and dropping an image from the Finder onto the opened Pages document or using the Pages Media tool to insert images from the Photos library. There are several options for image insertion.
There is a litany of word-processing applications that can work on macOS Sequoia. Many are in the Mac App Store and may require in-app purchases, or outright purchases (or subscriptions). Some are based on markdown, and others are more traditional.
There is the free LibreOffice Suite which is an MS Office clone with frequent updates. It offers a choice of Intel or Apple Silicon compiled versions. LibreOffice documentation (PDFs) is written in LibreOffice Writer and is reasonably comprehensive. Although I have Office 2021 for Mac, and Pages v14.3 installed, I also keep a current version of LibreOffice installed.
SoftMaker offers their Office 2024 for Mac which is a free trial, then paid (or subscription) MS Office clone. This likely would be my pick if I did not have Office 2021 for Mac installed.