It's easy to start a campaign for likes. You go to the Campaigns section in the sidebar of YTMonster.
Hereafter, you will need to press the New Campaign button.
Once you're on the "New Campaign" page, you simply enter your YouTube Video link in the first field. In the dropdown, you select "YouTube Likes"; hereafter, you press "Next".
In the amount field, you enter the number of likes you would like to receive.
After entering the information above, you can submit the campaign as long as you have sufficient credits. If you've done everything correctly, a campaign for likes should now be live in the Campaigns section.