Remote server change directory

C# WinSCP code logs into remote server and puts me in root/A folder. I want to go to folder root/B folder. How do I upload a file to root/B folder?
Code works to login, just can't get to the correct folder. When I run the code below, I get error: Cannot create remote file, no such file or directory. I'm sure it is trying to append to the root/A folder and I need it to go one step up to root then go to B folder.

SessionOptions sessionOptions = new SessionOptions
{
Protocol = Protocol.Sftp,
HostName = sftpHost,
UserName = sftpUsername,
Password = sftpPassword,
SshHostKeyFingerprint = "ssh-rsa ...",
SshPrivateKeyPath = @"P:\...",
};

using (Session session = new Session())
{
// Connect
session.Open(sessionOptions);

// Upload files
TransferOptions transferOptions = new TransferOptions();
transferOptions.TransferMode = TransferMode.Binary;

TransferOperationResult transferResult;
transferResult =
session.PutFiles(strFileName, "/root/b/filename.rec", false, transferOptions);

// Throw on any error
transferResult.Check();
}

Cadel wrote:

I'm sure it is trying to append to the root/A folder and I need it to go one step up to root then go to B folder.

No it's not. As you have specified an absolute path as /root/b/filename.rec, WinSCP is uploading exactly there. The home path (/root/A) is not involved at all.
Can you upload the file using WinSCP GUI?

Yes, using WinSCP application, I am able to get to root/B folder, and save file to root/B folder. When I login using WinSCP application the root/A folder is shown, then I click on the icon in the toolbar, "Parent directory" the folder with the up arrow, and then I'm in the parent folder and can see folder A and folder B. I double click folder B, then upload my file to folder B.
The account on the server defaults to root/A folder. I asked the admin to default my user account to folder B and she said "No".

So, in my code how do I change the directory? Currently my code appends folder B to folder A. So it looks like this "root/A/root/B/filename" I want just "root/B/filename".

I found the answer on Stackoverflow.
https://stackoverflow.com/questions/28027074/winscp-c-sharp-first-use