First of all you should concentrate on one method.
Lightbox is commonly used, so you should have a look at the tutorial on the lightbox website.
Then you have to edit your album page, assuming you want to open the lightbox window from the album page.
There are some changes in the header necessary as well as the call of the image itself.
You will find a good explanation in slyt's thread. Read the thread carefully and try to understand and follow each step.
Have fun fiddling with the code