There are two methods.
FIRST METHOD
you need to upload the picture with the real resolution size on the server. Example, save it just like in URL www.yourwebsite.com/album1/realpicture1.jpg
Then make its thumbnail to be viewed on the gallery, by resizing it in a software, or manually if you are using Microsoft Windows, just use Windows Paint, then upload the thumbnail picture. Example, save it just like in URL www.yourwebsite.com/album1/thumbnailpicture1.jpg
Then, make a page where the thumbnail will be laying down on the page by use this code:
<a href="www.yourwebsite.com/album1/realpicture1.jpg" target="_blank"><img src="www.yourwebsite.com/album1/thumbnailpicture1.jpg"></a>
SECOND METHOD
Just same as above, but just different in code and you don't need to make thumbnail picture because it wasting your time in process.
The code is below:
Like this: <a href="www.yourwebsite.com/album1/realpicture1.jpg" target="_blank"><img src="www.yourwebsite.com/album1/realpicture1.jpg" width="40" height="40"></a>
Note: you can change the "40", just depends what size of thumbnails what you need.
ADDITIONAL
Those ways will makes the picture will be enlarger in separate windows when they are click the thumbnail picture, if you want to make another enlarger link option, just simply use this code:
<img src="www.yourwebsite.com/album1/realpicture1.jpg" width="40" height="40">
<br><a href="www.yourwebsite.com/album1/realpicture1.jpg" target="_blank">Click here to enlarge photo</a></br>
That code will make an option titled "Click here to enlarge photo" below the thumbnail picture, and when someone click it, a new window will appear and will show the real size of the picture.
