How we share folder and file ?, via dropbox api

To share a folder, you should first call ShareFolderAsync. That takes a "path" parameter that should be the path to the folder that you want to share. The documentation explains how to check the result of that operation.

Once that's done, you should then call AddFolderMemberAsync to invite members to that shared folder. That takes the shared folder ID, from the first step above, as well as the list of members you want to invite (a list of AddMember instances).

That would look something like this:

var shareFolderLaunch = await this.client.Sharing.ShareFolderAsync ("/folder_to_share");
var sharedFolderId = "";
if (shareFolderLaunch.IsAsyncJobId) {
    while (true) {
        var shareFolderJobStatus = await this.client.Sharing.CheckShareJobStatusAsync(shareFolderLaunch.AsAsyncJobId.Value);
        if (shareFolderJobStatus.IsFailed) {
            Console.WriteLine ("Sharing folder failed: " + shareFolderJobStatus.AsFailed.Value);
            return;
        } else if (shareFolderJobStatus.IsInProgress) {
            Console.WriteLine ("Sharing folder in progress...");
            // todo: add some delay
        } else if (shareFolderJobStatus.IsComplete) {
            Console.WriteLine ("Sharing folder complete.");
            sharedFolderId = shareFolderJobStatus.AsComplete.Value.SharedFolderId;
            break;
        }
    }
} else if (shareFolderLaunch.IsComplete) {
    sharedFolderId = shareFolderLaunch.AsComplete.Value.SharedFolderId;
} else {
    return;
}

Console.WriteLine ("Shared folder with ID: " + sharedFolderId);

var members = new[] { new AddMember(new MemberSelector.Email("email@example.com")) };
await this.client.Sharing.AddFolderMemberAsync(sharedFolderId, members);