Image issues

Hi,
The images are not at full width on my page. When I upload an image, it remains in a small size on the page even thought I have set it to full res from the post editor page (in the dashboard). If I place the image in the gallery, then it’s wider on the page but it’s a bit blurry. It’s set to full resolution. I have placed this code to css, .section-inner.thin { max-width: 1000px; } to remove the narrowness. Hamilton’s theme demo shows the images in full size out-of-the-box. I want that my images are crispy, not blurry.