Not to worry - it's very easy. All you need is an external hard drive or a USB flash drive.
1- Copy your files from the old computer to the external drive or flash drive.
2- Move the files from the external drive or flash drive to the new computer. That's all there is to it!
The files that you can transfer in this way are your personal files, i.e., documents, pictures, spreadsheets, music, etc. Nothing else can be transferred between computers.
3- Files in your OneDrive don't need to be transferred, because they're on the internet.
For the future: The money that you and I and everyone else pay to Microsoft allows us to use the software. It does not pay for talking to someone at Microsoft. Indeed, there's no one to talk to - Microsoft employees don't support individual customers. Microsoft hires third-party contractors to talk or chat with customers, but there are only a limited number of them, so they're not easy to reach.