Click on the following links to install all the following tools
To check whether they were installed correctly.. go to command prompt, type
git --version

sfdx plugins --core

make sure that the current version of CLI is 45+ because development of lwc is supported from CLI with version greater than 45,
If your CLI version is 44, then try the below commands, one after the other
sfdx plugins:uninstall salesforcedx
sfdx update
re-check the version.. if version is still below 45 then execute.
sfdx plugins:install salesforcedx@pre-release
Open visual Studio, after installation from the above link..
click on the extensions in the sidebar.

Search for
1. Salesforce Extension Pack
2. Lightning Web Component
Install them.

Now, we have the basic setup ready so that we can start building the lightning web components.
But in up coming days we also need to install Nodejs for testing the lwc components using the jestjs framework.