i bought worms wmd from gog

but i dont know how to install that

there are 2 files to download
i dont know what to doing with the 2 files

Just click on them with the cursor.
The browser will open a window showing that the download is in progress.
You can also use Galaxy to download games, but I prefer to download them in my browser.

Two choices:

1. Install the Galaxy client to your computer and click the install button. That will download and install the game for you. This is somewhat similar what you'd do in e.g. Steam.

2. If you'd rather do it the old school way without any gaming clients, download the installer setup files with your web browser (one executable file, and one or several bigger binary files; or if the game is small, then it might even be in one executable file).

After you have downloaded the files to any folder in your computer (by default it is probably your "Downloads" folder in File Explorer), then go to that folder and click on the setup file (the one whose file type is shown as an application, not the bin file). The filename for both the executable and binary files starts with "setup".

Then just do what it instructs, remember to check the box which says you have read the instructions. After it is installed, the shortcut to the game can be found in your Start menu, like with any programs.