This can be tricky if you aren't used to computers so hopefully this will help. This tutorial is for downloading on your PC.
1. Open your gallery. Click on the 'select photos' button.
2. Over on the left you can click 'Select: All' to download all your images which will download in a zip folder. Or click on the individual images to download only the ones you want.
3. Once you have selected All images or just the ones you want, click on 'download' on the top right hand side.
If you are still having trouble let me know!