Help with writing a book please?

Hi, I have a bunch of 'snippets' about a page long each (hundreds of them) that I write when I am on public transport and I'm thinking of trying to put it all together into a book. My problem is trying to create and weave together these snippets with a story line. The snippets are mostly about 2 girls, one is your average 27 yo professional writer, one is living a live of debauchery and turmoil amongst her many love-lives and somehow their paths meet. So basically I'm asking for some tips on how to write a book or string together these snippets. I find I'm very good at setting a scene or a feeling but when it comes to having a beginning and an end to a story I get very stuck. I'm not looking to make money on the book, it's just something I'd like to achieve one day - to tie together my writings. Thanks