that’s a very broad question - are you looking to edit a site that you have already created and deployed with us? If yes, are you referring to the content (so, text and images) or the layout (the user interface)?
please do tell us a bit more about what you are trying to do so we can advise you!
in that case, you’ll need to update the content on your local copy - if you have a repo that is connected to your netlify site, commit the changes, push to the repo, and then after your build is completed you should see the live changes.
how did you deploy the initial site? like as i described or a different way?
Your repo (short for repository) is where the code for your website is kept. At Netlify, we support GitHub, GitLab, and Bitbucket. I would suggest getting started with this tutorial to learn more about the Netlify foundations.