1. According to official website, who plays games in Query Street, to download Dota2, you need to install StEAm in the form of a client.
2. search Dota2 in Steam. You can use the search bar or the game area on the main page of Steam to find the game, find Dota2, click the download button, and Steam will start downloading the game client.
3. after downloading, you can find Dota2 in the Steam game library. Double-click the icon to start installing the game. After the installation, you can start Dota2 directly from the Steam game library.