need help with a html question!

[ArcadiaReptiles]

so i finally found out how to use the lightbox and i absolutely love it. but ive been having this problem ever since i started making sites on photoshop. once ive done all the coding and css and everything and everything works fine i always have the same problem. pictures wont let me place them side by side. all the coding is fine but it wont have it.

This is what i mean here. the two smaller hatchlings pics ive used the lightbox on. there is no codes to break the line or cause a paragraph yet it wont go next to each other.
Arcadia Reptiles

if anyone here good with html could help me out id really appreciate it. or point me to the right direction. I can send my stylesheet and html to anyone who wants to have a look at it.