You would need to create your segments first. Sounds like job title is what you are aiming for? After you create the segmentation, you will need to create your snippet. Within the snippet, you will be able to select the segment you are wanting to be the deciding factor for which piece of content to show. There will be a default version which will show for anyone who is part of the default segment in your segmentation. Then, you will be able to customize the content per segment. Once you are satisfied with your snippet, you will then go to the landing page editor and add the snippet where you need it.
Marketo cookies users using munchkin codes. This code lets the system know who is on the page and will show the correct content.