Images not aligning properly when sliced?

I have to code a simple(ish) website for college for tomorrow- generally I know what I'm doing when it comes to HTML but because I haven't looked at it for a while now I'm a bit rusty. I've sliced up a 750px image that I want to use, and I'm exporting it from Photoshop as images only and just putting each image tag inside a 750px div. The images aren't aligning though- they're all over the place. I did have this problem once before and was able to fix it, but I've forgotten what I need to be doing and 'm rushed. Would anyone be willing to email and help me, maybe?