Installing an Operating System: A Complete Step-by-Step Practical Guide for Beginners

Introduction

Installing an OS sounds scary the first time, but it’s actually a simple process if you follow the right steps. In this guide, we’ll do it end to end: download the ISO, make a bootable USB, boot the PC, install the OS, and set it up for daily use.
We’ll use Ubuntu (Linux) as the main example (free and beginner-friendly). I’ve also added a quick Windows section so you can map the same steps there too. Keep it calm, follow one step at a time, and you’ll be done.

1) System Requirements

A quick checklist before you start:

Tips

Backup important data.

Note your boot menu key (F12/F10/Esc/Del).

If your PC is older, you may need Legacy/CSM. For new PCs, use UEFI + GPT.

2) Download the OS ISO File

A. Ubuntu (example)

Go to Ubuntu’s official site and download the desktop ISO (LTS is best).
Linux users can use terminal:

wget https://releases.ubuntu.com/24.04/ubuntu-24.04-desktop-amd64.iso

Output (example):

Saved: ‘ubuntu-24.04-desktop-amd64.iso’

B. Windows 11 (quick)

Go to Microsoft’s official page → Download ISO or use Media Creation Tool.

Always download from official sources only.

3) Create a Bootable USB

Method 1 (Windows) — Rufus (very easy)

Open Rufus.

Insert USB → Choose your ISO.

Partition scheme:

GPT (UEFI, new systems)

MBR (legacy BIOS)

Click Start → confirm format → wait till READY.

Method 2 (Linux/macOS) — dd command

Find your USB device (example: /dev/sdb). Be careful—this erases the USB.

lsblk

sudo dd if=ubuntu-24.04-desktop-amd64.iso of=/dev/sdX bs=4M status=progress oflag=sync

Replace /dev/sdX with your USB (e.g., /dev/sdb).
Output (example):

8589934592 bytes copied, 360 s, 23.8 MB/s

4) Boot from the USB

Keep the USB plugged in.

Restart PC → Press F12/F10/Esc/Del (boot menu).

Select your USB device.

You’ll see the installer screen.

Ubuntu first screen (example):

Try Ubuntu

Install Ubuntu

Choose Install Ubuntu.

5) Partition the Drive

Two options:

A. Beginner (recommended)

Erase disk and install Ubuntu → the installer will handle partitions automatically.

B. Manual Partition (custom / dual boot)

Basic safe layout (UEFI systems):

EFI System Partition: 512 MB, FAT32, mount /boot/efi

Root (/): 30–60 GB, ext4

Home (/home): remaining space, ext4 (optional but useful)

Swap: 2–8 GB (optional; can use swapfile later too)

Check disks (live session terminal):

sudo fdisk -l

Output (example):

Disk /dev/nvme0n1: 512 GB

/dev/nvme0n1p1  512M  EFI System

/dev/nvme0n1p2   60G  Linux filesystem  /

/dev/nvme0n1p3  430G  Linux filesystem  /home

/dev/nvme0n1p4    8G  Linux swap

6) Install the OS (Installer Screens)

Select Language, Keyboard, Wi-Fi (if needed).

Tick Install updates and 3rd-party software (helps drivers).

Choose Install type (Erase disk or Manual).

Set Timezone, Username, Password.

Click Install.

Installer messages you may see:

Copying files… 45%

Installing system… 78%

Installation complete.

When it says done, remove the USB and press Enter to reboot.

7) First Boot and Login

You’ll see the login screen. Enter your password.
Open Terminal and confirm version:

lsb_release -a

Output:

Distributor ID: Ubuntu

Description:    Ubuntu 24.04 LTS

Release:        24.04

Codename:       noble

8) Post-Installation Setup (do this now)

Update + base tools

sudo apt update && sudo apt upgrade -y

sudo apt install -y curl vim net-tools git

Enable firewall

sudo ufw enable

sudo ufw status

Output: Status: active

Quick network check

ip a

ping -c 3 google.com

Media codecs (optional)

sudo apt install -y ubuntu-restricted-extras

9) Windows 11 — Mini Install Guide (for reference)

Create USB with Media Creation Tool or Rufus + ISO.

Boot from USB → Install now.

Enter key (or “I don’t have a product key”).

Custom: Install Windows only.

Select/clean target drive (careful—deletes data).

Setup copies files → auto reboots → finish OOBE (region, account, privacy).

Run Windows Update → install drivers.

Dual-boot tip: Install Windows first, then Linux. Linux installer will detect Windows and add it to GRUB.

10) Common Errors and Quick Fixes

11) Handy Commands (you’ll actually use)

Disk space

df -h

CPU/RAM live view

top   # press q to quit

List hardware

lshw -short | less

Create a new admin user

sudo adduser newuser

sudo usermod -aG sudo newuser

12) Conclusion

That’s the full journey: ISO → bootable USB → boot → install → first login → updates → ready to use. Do this once or twice and it becomes second nature. If you’re learning IT, this is a core skill. Practice with different Linux distros, try manual partitions, and learn how bootloaders work—your confidence will shoot up.

13) FAQs

Q1. How long does a fresh install take?
Usually 15–40 minutes (SSD is faster than HDD).

Q2. Can I install without losing data?
Yes—use manual partitioning and don’t format your data partition. But always keep a backup.

Q3. GPT vs MBR—what to use?
Use GPT + UEFI on modern systems. Use MBR only for older BIOS machines.

Q4. Do I need internet for install?
Not required, but recommended for updates and drivers during setup.

Q5. Is dual-boot safe?
Yes. Install Windows first, then Linux. Keep backups and follow partitions carefully.