The first thing to consider - are you writing in good English? Now, I know you aren't a native speaker, so this is understandable, but it wouldn't hurt to run it through Grammarly.
As you can see, there are loads of basic errors.
Step two, possibly use something like this: https://www.semrush.com/swa/checker
I wouldn't use this, but for an SEO newbie it might be a nice tool to use. If it's not free (not 100% sure) there are a few free content optimization tools available on the web.
I would suggest link building, but right now I'd just focus on the basics. Both steps above will help you with this.
ps- FYI, A friend and I did a two-day audit on Fiverr. Their SEO is shocking. Take WWW. from your link and it redirects to the wrong page. Major facepalm.
Good luck though, their authority in general should make the page rank!