Two options based on your needs.
You are using a checkbox. Does that mean that more than one of these can be checked at any point? Will you need to show a different image for each one that is checked?
If that is not the case and you only need one selection at a time then use FileMaker's "Hide When" functionality to show the image on the right or hide it as appropriate.
If that is the case then you might want to use a portal (I would hide the fact that it is a portal and just show the images) that shows related records based on the selection and in those related records are images. That method would allow you to "stack" your help images to the right of what is checked.
Take a look at popovers.
Clicking the check box can trip the OnObjectModify Script trigger. The script performed by the trigger can open a popover and use it to display your information. The script can either link to a related record and use fields from the related record to show info specific to the option selected or it can set a merge variable (if the info is text) to a value and the merge variable can be placed inside the popover.
A script can use go to object to open a popover. (Open the popover while in layout mode, select the Popover panel that opened and use the Name box on the Inspector's position tab to give it an object name that you then use in your script to open the popover.
That popover button can be made permanently invisible by entering 1 or True as it's Hide Object When setting.