The short answer
Go to Sites, Chat Widget, click New and pick a type such as Live Chat, SMS/Email chat, WhatsApp, Voice AI or All-in-one. Customize its style, chat window and messages, save, then either select it in a HighLevel website or funnel's settings or copy the code with Get Code and paste it into any other site.
Pick the right chat type
HighLevel describes Live Chat (called Web Chat in Conversations) as real-time messaging best for teams with round-the-clock coverage. SMS/Email chat collects the visitor's details so you can reply later by text or email, which suits small teams that are not always online. WhatsApp, Facebook and Instagram chat open conversations in those apps, and Voice AI chat lets visitors talk to an AI agent in the browser. All-in-one chat combines your connected channels in a single widget. Conversation AI can also answer inside the widget when no one is available, and every message lands in the Conversations inbox.
Create and customize the widget
Open Sites, Chat Widget, click New and choose the type. Setup has three pages, or four for types that use AI. Style covers theme, icon, welcome message, avatar, size and placement (sticky, or embedded inline on the page). Chat Window covers the title, intro message, contact form, and a compliance notice with an optional consent checkbox that you can make required. Messaging sets acknowledgements and the widget language, and Agent picks the AI agent where supported. Turning on Load on user interaction waits to load the widget until the visitor scrolls, clicks or taps, or about 8 seconds pass, which helps page speed.
Install it on your site
For a HighLevel website or funnel, open its settings, select the widget in the Chat Widget section and save. Alternatively, open the page editor, click the Tracking Code icon, paste the widget code and save. For WordPress or another platform, click Get Code, copy the snippet and add it to the site's code or through Google Tag Manager. HighLevel notes that some A2P registration flows check that the chat widget is live on your website, so install it before submitting if you are using Chat Widget Setup for SMS consent. Send yourself a test message and confirm it shows up in Conversations.
More answers in HighLevel questions. For costs, see GoHighLevel pricing or run the cost calculator.