how to make preview images

[themrsweb]

how do you make the preview images for each product show up they are only showing no image they also show an image once the link is shown on that image that was uploaded is showing up fine and clear it is only the preview for the product that is not being shown

[abantecart]

Welcome to AbanteCart.

Do you get any errors or warnings in the log?
Possibly, images or thumbnails directory has no write permissions.

[themrsweb]

public_html/core/engine/resources.php on line 353
it says critial error
i could not find the error or correct it.
could that be where the problem is at?