Create Basics.md

Original file name: Sample3_PersistentAgents_Basics.md, cleaned up the sample code, using uri. first pass.

Author: RobiladK

doc-samples/agents/c#/azure-ai-agent-sdk/Basics.md

@@ -0,0 +1,156 @@
+# Sample for basic use of an agent in Azure.AI.Agents.
+
+In this example we will demonstrate creation and basic use of an agent step by step.
+
+1. First get `ProjectEndpoint` and `ModelDeploymentName` from config and create a `PersistentAgentsClient`.
+```C# Snippet:AgentsOverviewCreateAgentClient
+var projectEndpoint = configuration["ProjectEndpoint"];
+var modelDeploymentName = configuration["ModelDeploymentName"];
+PersistentAgentsClient client = new(new Uri(projectEndpoint), new DefaultAzureCredential());
+```
+
+2. Next we will need to create an agent.
+
+Synchronous sample:
+```C# Snippet:AgentsOverviewCreateAgentSync
+PersistentAgent agent = client.CreateAgent(
+    model: modelDeploymentName,
+    name: "Math Tutor",
+    instructions: "You are a personal math tutor. Write and run code to answer math questions."
+);
+```
+
+Asynchronous sample:
+```C# Snippet:AgentsOverviewCreateAgent
+PersistentAgent agent = await client.CreateAgentAsync(
+    model: modelDeploymentName,
+    name: "Math Tutor",
+    instructions: "You are a personal math tutor. Write and run code to answer math questions."
+);
+```
+
+3. We will create thread as a separate resource.
+
+Synchronous sample:
+```C# Snippet:AgentsOverviewCreateThreadSync
+PersistentAgentThread thread = client.CreateThread();
+```
+
+Asynchronous sample:
+```C# Snippet:AgentsOverviewCreateThread
+PersistentAgentThread thread = await client.CreateThreadAsync();
+```
+
+4. We will add the message to the thread, containing a question for agent. This message must have `User` role.
+
+Synchronous sample:
+```C# Snippet:AgentsOverviewCreateMessageSync
+client.CreateMessage(
+    thread.Id,
+    MessageRole.User,
+    "I need to solve the equation `3x + 11 = 14`. Can you help me?");
+```
+
+Asynchronous sample:
+```C# Snippet:AgentsOverviewCreateMessage
+await client.CreateMessageAsync(
+    thread.Id,
+    MessageRole.User,
+    "I need to solve the equation `3x + 11 = 14`. Can you help me?");
+```
+
+5. Now we will need to create the run, which will assign agent to the thread.
+
+Synchronous sample:
+```C# Snippet:AgentsOverviewCreateRunSync
+ThreadRun run = client.CreateRun(
+    thread.Id,
+    agent.Id,
+    additionalInstructions: "Please address the user as Jane Doe. The user has a premium account.");
+```
+
+Asynchronous sample:
+```C# Snippet:AgentsOverviewCreateRun
+ThreadRun run = await client.CreateRunAsync(
+    thread.Id,
+    agent.Id,
+    additionalInstructions: "Please address the user as Jane Doe. The user has a premium account.");
+```
+
+6. It may take some time to get the response from agent, so we will wait, when it will get to the terminal state. If the run is not successful, we will raise the assertion error with the last error message.
+
+Synchronous sample:
+```C# Snippet:AgentsOverviewWaitForRunSync
+do
+{
+    Thread.Sleep(TimeSpan.FromMilliseconds(500));
+    run = client.GetRun(thread.Id, run.Id);
+}
+while (run.Status == RunStatus.Queued
+    || run.Status == RunStatus.InProgress);
+```
+
+Asynchronous sample:
+```C# Snippet:AgentsOverviewWaitForRun
+do
+{
+    await Task.Delay(TimeSpan.FromMilliseconds(500));
+    run = await client.GetRunAsync(thread.Id, run.Id);
+}
+while (run.Status == RunStatus.Queued
+    || run.Status == RunStatus.InProgress);
+```
+
+7. Print the agent's messages to console in chronological order.
+
+Synchronous sample:
+```C# Snippet:AgentsOverviewListUpdatedMessagesSync
+PageableList<ThreadMessage> messages = client.GetMessages(
+        threadId: thread.Id,
+        order: ListSortOrder.Ascending);
+
+foreach (ThreadMessage threadMessage in messages)
+{
+    foreach (MessageContent contentItem in threadMessage.ContentItems)
+    {
+        if (contentItem is MessageTextContent textItem)
+        {
+            Console.Write($"{threadMessage.Role}: {textItem.Text}");
+        }
+        Console.WriteLine();
+    }
+}
+```
+
+Asynchronous sample:
+```C# Snippet:AgentsOverviewListUpdatedMessages
+PageableList<ThreadMessage> messages = await client.GetMessagesAsync(
+        threadId: thread.Id,
+        order: ListSortOrder.Ascending);
+
+foreach (ThreadMessage threadMessage in messages)
+{
+    foreach (MessageContent contentItem in threadMessage.ContentItems)
+    {
+        if (contentItem is MessageTextContent textItem)
+        {
+            Console.Write($"{threadMessage.Role}: {textItem.Text}");
+        }
+        Console.WriteLine();
+    }
+}
+```
+
+8. Clean up resources by deleting thread and agent.
+
+Synchronous sample:
+```C# Snippet:AgentsOverviewCleanupSync
+client.DeleteThread(threadId: thread.Id);
+client.DeleteAgent(agentId: agent.Id);
+```
+
+Asynchronous sample:
+```C# Snippet:AgentsOverviewCleanup
+await client.DeleteThreadAsync(threadId: thread.Id);
+await client.DeleteAgentAsync(agentId: agent.Id);
+```