How do I add extra space to the disk?

Hello,
Disk space is full:
Code:$ sudo df -h
Filesystem Size Used Avail Use% Mounted on
udev 1.9G 0 1.9G 0% /dev
tmpfs 390M 564K 389M 1% /run
/dev/xvda1 3.6G 3.5G 0 100% /
tmpfs 1.9G 0 1.9G 0% /dev/shm
tmpfs 5.0M 0 5.0M 0% /run/lock
/dev/xvda6 5.3G 247M 4.8G 5% /home
tmpfs 390M 0 390M 0% /run/user/0
tmpfs 390M 0 390M 0% /run/user/1000And:
Code:$ sudo lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINTS
sr0 11:0 1 16M 0 rom
xvda 202:0 0 10G 0 disk
xvda1 202:1 0 3.6G 0 part /
xvda2 202:2 0 1K 0 part
xvda5 202:5 0 976M 0 part [SWAP]
xvda6 202:6 0 5.4G 0 part /homeI added extra disk space:
Code:$ sudo lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINTS
sr0 11:0 1 16M 0 rom
xvda 202:0 0 20G 0 disk
xvda1 202:1 0 3.6G 0 part /
xvda2 202:2 0 1K 0 part
xvda5 202:5 0 976M 0 part [SWAP]
xvda6 202:6 0 5.4G 0 part /homeNow I want to add this extra space to / using fdisk tool. How can I do it?

Thank you.