I hope you have a Live USB already , if not you have to create it .
- get pendrivelinux software , for creating Live USB from windows .
2.follow these steps
Select Ubuntu Desktop Edition from the dropdown list.
click at browse and select your ISO file .Then click at create .this will create a live USB for you from windows .
for this part credit goes here :Ubuntu.com
Now we have to configure the BIOS settings as Removal disk should be as 1st boot priority and HDD as 2nd . Now connect your USB and your PC will boot and take you to installation process .
After Ubuntu loading , you will get like this , choose Install Ubuntu .Then it will directs you to Preparing to install Ubuntu where it will check about minimum requirement . Internet connection doesn't matter but you should have minimum empty space as its mentioned .Then click at continue.Then next step is allocate drive step ,look at the image . , here you have to choose what kind of install you want to give . each type have its clear description , so you can easily understand . there partitioning you have to mention . make sure that you have selected an empty partition for Ubuntu install or a partition which you dont want .
you have to select the partition and you have to select it as EXT4/EXT3 and then mount point as / then click at create . Size is your wish but make sure about the minimum size (> 5 GB) .Creating swap is a good move .
more information on swap will be here : swapfaq.
Remaining steps are something like keyboard layout,languages and times Zones . I hope you can handle them safely .
Credit goes to :techspot.com softpedia