how do i do this?

Hi friends. Because I'm absolutely sure that some of you out there (and apparently there are a lot more of you than I thought) know how to do fancy things on Photoshop (Brit, I'm thinking of you), I was hoping you could tell me how to do some things. I'll send you a postcard as a reward.

Problem a: The fancy white background collage with photos and dresses and lots of different things.

Problem b: The photo collage.

Problem c: The simple linked photo (I'd love how to do two and four photos like this).

Thanks in advance to whoever bails me out. I've been wanting to know how to do this stuff forever and I finally have access to Photoshop, hooray!