Dear sirs, for manufacturing company of silicon solar cells needs assistance in upgrading a SharePoint system (export data from one SharePoint account to another and update the SharePoint version to the last one)

I am looking for someone to help me upgrade my SharePoint system. Currently I'm not sure if I have access to both SharePoint accounts, but I need my data exported from one to the other and the SharePoint version to be upgraded to the latest release. There is no specific deadline for this project. So if you are an expert when it comes to SharePoint systems and can help me with this task, I'd love to hear from you!