There is no immediate problem but you should act soon.
Hackers are always trying to find new ways to break into commonly used Windows versions, and Microsoft are always trying to find the flaws and fix them. But from today, they won't be fixing the security flaws in Windows 7 any more. So as time goes on, it becomes more and more likely that your PC gets compromised. Antivirus software can only do so much - if the OS is out of date, it's like a house on a crumbling foundation.
(The same issues affect old versions of other OSes such as Linux or iOS. They also affect software you run but the impacts tend to be less serious.)
Remember the Wannacry in 2017 attack that seriously disrupted the NHS? That's what can happen when you run Windows past its end of support. That affected Windows XP, three years after end of support for that.
As mentioned, buying a new PC is the easiest solution.
If you want to upgrade, you can download Windows 10 from Microsoft here: www.microsoft.com/en-gb/software-download/windows10ISO . In my experience a Windows 7 product key will activate Windows 10. Or as others have mentioned you can download a Linux distribution.
Then the steps I would take to upgrade are:
If you have paid-for programs, make sure you have the product keys for them and make sure they will still activate. You can get software that'll show you the product keys for the programs installed on your PC.
Ensure you have a copy of your files, or even better a backup of your whole Windows 7 install.
Install Windows 10 either as an 'upgrade' or a clean install.