xwells2020, as far as I know there is no direct converter. So,
1. Open the page of the website, the template of which you liked, in HTML codes mode. The other variant – open the file of the template in HTML Editor.
2. Insert uCoz codes in the necessary places (they look like $СODЕ$) and redraw all the graphic elements LOGO, pictures, buttons e.t.c.
3. Transfer the changed template from the Editor to your uCoz website.
4. Manage the design (CSS) for the website of yours.
5. Look at the results and enjoy!
That is why it takes time to adapt Wordpress template. If you do not know HTML and CSS you shouldn't even try. Think about it! Maybe default templates or the templates that are already on the website will work for you. It will save you time. If you still want to do it – there is official ucoz forum. Ask your questions about it there. Good luck!