For Windows:

• Download the latest release here. Make sure that you are downloading the appropriate file, specially check whether your operating system type is 32-bit or 64-bit.
• The downloaded binary file has extension exe. Run it. It will prompt an installation wizard.
• Click Next.
• Accept the licence agreement and click Next.
• Select Complete Installation.
• Click on Install. It might prompt a window for asking administrator's permission. Click Yes.
• After installation click on Finish.
• Now, the mongodb is installed on the path  C:/Program Files/MongoDB/Server/3.2/bin.  Instead of version 3.2, there could be some other version for your case. The path name would be changed accordingly.
• bin directory contain several binary file along with mongod and mongo. To run it from other folder, you could add the path in system path. To do it:

1.  Right click on My Computer and select Properties.
2. Click on Advanced system setting on the left pane.
3. Click on Environment Variables... under the Advanced tab.
4. Select Path from System variables section and click on Edit....
5. Before Windows 10, append a semi-colon and paste the path given above. From Windows 10, there is a New button to add new path.
6. Click OKs to save changes.

• Now, create a folder named data having a sub-folder named db where you want to run the server.
• Start command prompt from their. Either changing the path in cmd or clicking on Open command window here which would be visible after right clicking on the empty space of the folder GUI pressing the Shift and Ctrl key together.
• Write the command to start the server:

It would start the server on port 27017 by default.

• Open another command prompt and type the following to start client: 

• By default it connects to the test database. If you see the line like connecting to: test. Then you have successfully installed MongoDB. Congrats! Now, you can test Hello World to be more confident.