1. What is the VCL Style?

See documentation about it:

http://docwiki.embarcadero.com/RADStudio/Tokyo/en/Working_with_VCL_Styles

2. How to install VCL Style?

Copy new VCL Styles to the specific folder where all other VCL styles are available...

For XE3-XE5:

C:\Users\Public\Documents\Embarcadero\Rad Studio\XX.0\Styles

For XE6-Tokyo:

C:\Users\Public\Documents\Embarcadero\Studio\XX.0\Styles

For more information, please, read documentation:

http://docwiki.embarcadero.com/RADStudio/Tokyo/en/VCL_Styles_Overview

3. How to add new VCL Styles in my project?

- Open Project > Options > Application > Appearance page.

- In "Custom Styles" list you can see additional styles below "www.delphistyles.com" header.

- Select styles, which you want to use in your application.

- Use TStyleManager.TrySetStyle('name') to load style.

For more information, please, read documentation:

http://docwiki.embarcadero.com/RADStudio/Tokyo/en/Application_Appearance

4. Can I edit VCL Style from www.delphistyles.com?

Yes, you have full rights to edit, rename style as you want.

To edit and test it, you must use Bitmap Style Designer tool.

For more information, please, read documentation:

http://docwiki.embarcadero.com/RADStudio/Tokyo/en/Bitmap_Style_Designer

Information about how to export / import images from VCL Style in Bitmap Style Designer:

http://docwiki.embarcadero.com/RADStudio/Tokyo/en/Working_with_Images_in_the_Bitmap_Style_Designer