code snippet that shows how to create and send an envelope using the DocuSign .NET client

CreateAndSendEnvelope.cs

// Read a file from disk to use as a document
byte[] fileBytes = File.ReadAllBytes("[PATH/TO/DOCUMENT/TEST.PDF]");

EnvelopeDefinition envDef = new EnvelopeDefinition();
envDef.EmailSubject = "[DocuSign C# SDK] - Please sign this doc";

// Add a document to the envelope
Document doc = new Document();
doc.DocumentBase64 = System.Convert.ToBase64String(fileBytes);
doc.Name = "TestFile.pdf";
doc.DocumentId = "1";

envDef.Documents = new List<Document>();
envDef.Documents.Add(doc);

// Add a recipient to sign the documeent
Signer signer = new Signer();
signer.Name = "[SIGNER_NAME]";
signer.Email = "[SIGNER_EMAIL]";
signer.RecipientId = "1";

// Create a |SignHere| tab somewhere on the document for the recipient to sign
signer.Tabs = new Tabs();
signer.Tabs.SignHereTabs = new List<SignHere>();
SignHere signHere = new SignHere();
signHere.DocumentId = "1";
signHere.PageNumber = "1";
signHere.RecipientId = "1";
signHere.XPosition = "100";
signHere.YPosition = "150";
signer.Tabs.SignHereTabs.Add(signHere);

envDef.Recipients = new Recipients();
envDef.Recipients.Signers = new List<Signer>();
envDef.Recipients.Signers.Add(signer);

// set envelope status to "sent" to immediately send the signature request
envDef.Status = "sent";

// Use the EnvelopesApi to send the signature request!
EnvelopesApi envelopesApi = new EnvelopesApi();
EnvelopeSummary envelopeSummary = envelopesApi.CreateEnvelope(accountId, envDef);

// print the JSON response
Console.WriteLine("EnvelopeSummary:\n{0}", JsonConvert.SerializeObject(envelopeSummary));