how do I make thumbnails show up in rows?

Hi there, and thanks for assisting, I’m completely new! I am building a practice site, thievish.com, and I’m uploading pics and would like them to be same size thumbnails and across the whole page. like a photo gallery. I appreciate you helping me with this; I’ve been staring at the page for 3 days now trying to figure it out. I used the GoDaddy default template in the beginning and the pics I uploaded were all in line, very nicely. about 4 across. Anything I tried to upload after, however, was mis-sized, not placed proportionately, etc. Help!!