I need help in upgrading my MacBook Pro to macOS version 10.13 or later

If you want to install a newer OS that is called an Upgrade. 

The model and year of your Mac will determine which macOS you can upgrade to,

read Section 1 in the following links.

How To Upgrade To macOS Mojave - Apple Support

How to upgrade to macOS High Sierra - Apple Support

How to upgrade to OS X El Capitan - Apple Support

Before upgrading make a full back up of your Mac.

Check that third party apps you use have updates available for the new OS.

https://roaringapps.com

Check that your printers/ scanners etc have updated drivers and software available for the new OS.

If you are considering upgrading to Catalina be warned that it does not support 32bit apps.

Your Mac is probably running 32bit apps and these will need to be updated to 64bit apps,

some updates may be free, some may be paid. Use this app to discover which apps you have

are 32bit, https://www.stclairsoft.com/Go64/. Once the list has been created you can then

contact the developers of the apps to see if they provide 64bit updates. 

How to upgrade to macOS Catalina – Apple Support

You don't state what your problem is or what is happening to prevent you. What specifically are you doing? I suggest you provide your Mac year and model. Some Macs can only be upgraded to certain OSs. The Apple help site has specific instructions for how to do upgrades and deal with these problems. If you don't help us to help you, there is no way we can respond with useful information.