Building with Custom GPTs (Hands-On)

Time to turn your plan into a working chatbot. In this lesson, you will build a Custom GPT step by step using ChatGPT's GPT Builder. By the end, you will have a functional chatbot you can test and share.

Prerequisites

• A ChatGPT Plus ($20/month), Team, or Enterprise subscription
• Your completed planning worksheet from the previous lesson
• A desktop browser (the GPT Builder works best on desktop)

Step 1: Open the GPT Builder

1. Go to chat.openai.com
2. Click your name or profile icon in the bottom-left
3. Select My GPTs
4. Click Create a GPT

You will see two tabs at the top:

• Create: A conversational interface that guides you through setup
• Configure: Direct access to all settings

We will use Configure mode for more control.

Step 2: Set the Name and Description

Click the Configure tab and fill in:

• Name: Your chatbot's name from the planning worksheet
• Description: A one-sentence summary of what it does

Example:

• Name: HR Onboarding Assistant
• Description: Answers new employee questions about company policies, benefits, first-week schedule, and office logistics.

Keep the description clear and specific. It appears when users find your GPT and helps them understand what it does.

Step 3: Write the Instructions

The Instructions field is the most important part. This is where you tell your GPT how to behave. Paste your planning worksheet details and expand them into clear instructions.

Structure your instructions like this:

Example instructions for an HR Onboarding Assistant:

Step 4: Add Conversation Starters

Scroll to the Conversation Starters section. You can add up to four pre-written prompts that appear as clickable buttons when a user opens your GPT.

Use the conversation starters from your planning worksheet:

Example:

1. "What benefits do I get as a new employee?"
2. "Walk me through my first-week schedule"
3. "What forms do I need to complete?"
4. "Tell me about the office and parking"

Tips for effective starters:

• Start with an action verb or question word
• Be specific enough to get a useful response
• Cover your chatbot's main use cases
• Avoid generic prompts like "Help me" or "Hello"

Step 5: Configure Capabilities

Under Capabilities, you can enable or disable:

Capability	What It Does	When to Enable
Web Browsing	Searches the internet for current info	When your chatbot needs up-to-date data
DALL-E Image Generation	Creates images from text	When your chatbot needs to generate visuals
Code Interpreter	Runs Python code, analyzes files	When your chatbot works with data or calculations

For most chatbots, you can keep Web Browsing on and disable the others unless you specifically need them.

Step 6: Upload a Profile Picture

Click the profile picture area to either:

• Generate an image using DALL-E (click the generate button)
• Upload your own image

A good profile picture makes your GPT look professional and helps users identify it quickly.

Step 7: Test Your GPT

Click Preview on the right side of the builder to test your GPT. Try these tests:

Test 1: Happy Path

Ask a question your chatbot should handle well. Does it respond correctly and in the right tone?

Test 2: Boundary Test

Ask something outside your chatbot's scope. Does it politely redirect?

Test 3: Specificity Test

Ask a detailed question. Does it give a specific answer or a vague one?

Test 4: Conversation Starters

Click each conversation starter. Do the responses make sense?

Common issues and fixes:

Problem	Fix
Responses are too long	Add "Keep responses under X words" to instructions
Wrong tone	Be more explicit about tone in instructions (add examples)
Ignores boundaries	Strengthen boundary language: "You MUST NOT..."
Too generic	Add more specific instructions and examples
Makes up information	Add "Only answer based on your knowledge files"

Step 8: Iterate on Instructions

Based on your testing, refine the instructions. This is normal—most GPTs need two or three rounds of adjustment. Common refinements:

• Adding example responses to show the desired format
• Strengthening boundary rules
• Adding edge case handling ("If the user asks X, respond with Y")
• Adjusting response length guidelines

Quick Reference: GPT Builder Settings

Setting	Where to Find It	What to Enter
Name	Configure > Name	Your chatbot's name
Description	Configure > Description	One-sentence summary
Instructions	Configure > Instructions	Full behavior guide
Conversation Starters	Configure > Conversation Starters	Up to 4 prompts
Knowledge	Configure > Knowledge	Upload files (next lesson)
Capabilities	Configure > Capabilities	Toggle features on/off
Profile Picture	Click the icon	Upload or generate

Key Takeaway

Building a Custom GPT is a process of writing clear instructions, testing, and refining. The GPT Builder makes it simple—your planning worksheet translates directly into the Configure fields. Do not aim for perfection on the first try. Build a basic version, test it, and improve. In the next lesson, you will build the same chatbot on Claude Projects to compare the experience.