Explanation
1. Login into your Themeforest account and click on "Downloads".
2. Select your template and click on "Download".
3. Download "All files & documentation".
4. Extract the .zip/.rar File.
5. Login to your dashboard (yourblod.tld/wp-admin/index.php) and click on themes.
6. Click on "Add New".
7. Click on "Upload".
8. Click on "Choose File".
9. Select the main file and click on "Open".
10. Now click on "Install Now".
11. "Activate" the template.
12. Now you could "Customize" your template (see "Default customization").
12+. Please note that every template work other and if you need personal help only write me an email.