Telegram is a popular, cloud-based mobile and desktop messaging app known for its speed, security, and large file size support.

Here is a general guide on how to use the Telegram Messenger app:

1. Getting Started
Download and Install: Search for "Telegram" in the Google Play Store (Android) or App Store (iOS) and install the app.

Create an Account:

Tap Start Messaging.

Enter your country and mobile phone number.

Enter the verification code sent to your number via SMS or a phone call from Telegram.

Enter your name and, optionally, set a profile picture.

Sync Contacts: The app will usually ask permission to sync your phone's contacts to show you which friends are already using Telegram.

2. Basic Messaging and Communication
Start a Chat:

Tap the pencil icon (usually in the bottom corner on mobile) or the menu icon (three lines) to find the option for a "New Message" or "Contacts."

Select a contact from your list or search for someone by their username (if you know it).

Send a Message: Type your message in the text box and press the Send button (usually a paper airplane icon).

Send Media & Files: Tap the paperclip icon to attach photos, videos, documents (up to 2GB each), contacts, or your location.

Voice & Video Calls: In a one-on-one chat, tap the contact's name or profile picture at the top, then look for the phone or video camera icon to start a call.

Saved Messages: This is a cloud-based storage space for your personal use. You can forward messages, media, and files to this chat to save them and access them from any of your logged-in devices.

3. Key Features
Groups:

Create large group chats (up to 200,000 members) by selecting "New Group" from the main menu.

Groups can have administrators with various rights, and include features like polls, pinned messages, and group voice chats.

Channels:

Channels are a tool for broadcasting messages to an unlimited audience. Only administrators can post.

They are great for sharing news, updates, or content with followers.

Secret Chats:

To start a highly private, end-to-end encrypted conversation, select "New Secret Chat" with a contact.

These chats are device-specific, cannot be forwarded, and can feature self-destruct timers for messages.

Bots:

Telegram bots are automated third-party programs that can perform various tasks, from providing news and reminders to playing games or integrating other services.

You interact with them by sending commands (starting with a /) or tapping buttons.

Customization and Organization:

Chat Folders: Organize your chats into customizable tabs (e.g., "Work," "Family," "Unread") to keep your main chat list tidy.

Themes: Change the appearance of the app with various themes and color settings.

4. Privacy and Security
Username: You can set a public username in your settings, allowing people to find and message you without knowing your phone number.

Privacy Settings: In Settings > Privacy and Security, you can control who can see your phone number, last seen/online status, profile photo, and who can add you to groups and channels.

Two-Step Verification (2FA): It's highly recommended to set a cloud password in addition to the SMS code, which is an extra layer of security for logging into a new device.