Hi @Simona Bushevska
If you want to store documents in Document library, you could use sync function to store them in OneDrive:
Or if you want to store the whole sites, you could back up the site first, then store it in could. Below is a method to back up and restore a site using SharePoint 2019 Management Shell (according to your SharePoint version):
You could use two SharePoint Server 2019 Management shell command to achieve your requirement:
1.Use this command to back up your site collection
Backup-SPSite -Identity "http://sp/sites/luyi" -Path "C:\backup\portal.bak" -Force -NoSiteLock -Confirm:$False
2.Just copy the backup file to the cloud, if you want to restore it on your server, you could use this SharePoint Server 2019 Management shell command to restore this site collection from your PC location:
Restore-SPSite "http://sp/sites/luyi" -Path "C:\backup\portal.bak" -Force -Confirm:$False
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