hello. i would like to know if it's possible to show my posts not only in my homepage but also in other pages.

Do you mean you want your posts to show up on 3rd party websites as well? Or other pages in your own website?

in my own website.

What website platform? If you use e.g. WordPress your post is automatically shown on the relevant category, tag and date pages as well.

for that you need to set up relationship between different post in different category or you need to fir custom select query from database where you store your post and place those code to the page where you want to display post as per select query use for database.