Any Guide Backlinks for SEO Beginners

Hi! I am new to SEO and trying to acquire backlinks for my business niche (native plant gardening in Ontario). I've been researching how to find backlinks and most tutorials recommend looking for other related blogs and guest posting. The problem is that I am having trouble finding relevant blogs to do so.

Any guidance on finding niche backlinks would be appreciated!

Gustavo Woltmann.