You know there are some basic step to redeem Microsoft code
1. Go to microsoft.com/redeem.
2. Enter your Microsoft account credentials when prompted, unless already signed in.
3. Enter your 25-character code.
4. Click Next.
5. Click Confirm to add the product to your account.
Redeem a gift card or code on Windows 10
At first sign in to your Microsoft account using credentials like email, phone, and Skype ID.
Now go to the Taskbar and click on the Microsoft Store icon to open the app.
On the visible screen, hit See more (…) option then select Redeem Code from the context menu.
Succeeding after, type the 25 character code in the void box which you want to redeem and click on the Redeem button.
Regards, Jimmy Wick