wordpress problems pictures

[Deus]

I have a wordpress site with pictures but I'm having trouble putting my gallery, which is the size = "large" is too small and the size = "full" is too big

 

[deliteblogger]

Media Settings / Image sizes ?

I'm not sure about it though, maybe the screenshot is from a plugin's page. Check here: http://www.robyardman.com/wordpress/controlling-image-sizes-in-wordpress