Dual-boot

First create a partition for installing there Ubuntu

Instal the .iso from ubuntu webside
Install rufus
Install the ubuntu iso into a pendrive using rufus software

Restart the pc and setup the usb as the first option to boot

In the ubuntu installer, configure all ass you want untill the "Installation type" where you should check the "Something else" option

There select the free space, create a new partition in the "+" button, and assing 2048 mb of space as a primary type partition and use as swap partition.
The rest of space create a partition as a primary partition with format Ext4 and mount point in "/"
Then continue with the installation

Shared folder between systems

Create a new ntfs partition (in ubuntu you can install GParted)
Mount the new partition
Create a folder in the root where you want to share files

sudo mount -t ntfs o rw /dev/*partition* /forder/