The following class will create a "TextFile.txt" in "MyFolder" folder of the sharepoint.
Class GITS_Testing
{
public static void main(Args _args)
{
System.UriBuilder builder = new System.UriBuilder("https://osoolbh.sharepoint.com/sites/Testing");
str extId = xUserInfo::getExternalId();
Microsoft.Dynamics.AX.Framework.FileManagement.SharePointDocumentStorageProvider provider;
Microsoft.Dynamics.AX.Framework.FileManagement.DocumentLocation documentLocation = new Microsoft.Dynamics.AX.Framework.FileManagement.DocumentLocation();
provider = new Microsoft.Dynamics.AX.Framework.FileManagement.SharePointDocumentStorageProvider("osoolbh.sharepoint.com", "sites/Testing", "Shared%20Documents/MyFolder", extId);
System.Byte[] reportBytes = new System.Byte[0]();
System.Text.ASCIIEncoding enc = new System.Text.ASCIIEncoding();
reportBytes = enc.GetBytes("AY");
System.IO.MemoryStream memoryStream = new System.IO.MemoryStream(reportBytes);
documentLocation = provider.SaveFile(newGuid(), 'TextFile.txt', System.Web.MimeMapping::GetMimeMapping('TextFile.txt'), memoryStream);
}
}