First, You need to visit Microsoft's official SQL Server 2017 download page, then select the edition you want to download.
How to Download and Install SQL Server?
After you finish downloading the file, you need to choose to download the file to your computer, then run the setup.exe file.

Select Installation

Next, Select New SQL Server stand-alone installation or add features to an existing installation

Select the version SQL Server you want to install, then enter the product key.

Check select "I accept the license terms", then click the Next button

You can check select "Use Microsoft Update to check for update (recommended)", then click the Next button

Click Next to continue installation

Click Select All, or you want to select the component you want to install, then click the Next button

You need to download JRE runtime, then install to your computer. Next, click the Re-run button to check again.

If everything looks good, you can click the Next button to continue

You can enter your Instance ID or use the default name, then click the Next button

Click the Next button to continue installation

Click the Next button to continue installation

You can select mixed mode, then enter sql account.
But I recommend you choose to "Add Current User", then click the Next button

Click "Add Current User" button, then click the Next button

Click the Next button to continue installation

Click the Next button to continue installation

Click "Add Current User" button, then click the Next button to continue installation

Click the Next button to continue installation

Click Accept button, then click the Next button to continue installation

Click Accept button, then click the Next button to continue installation

Click the Install button to continue installation

Clic the Next button to complete installation
