Not sure if there is a guide out there but it's pretty easy and I can help you through it. First you'll need to make an account name and password. I remember it prompting for it the first startup but if not look through the options. Then you'll want to set the path to your music library in preferences -> shares. These are the files that you're making available to people searching and downloading. Then go to preferences -> downloads -> folders. I like to set my download folder as separate from my music library so that I can standardize it to my naming conventions, clean up metadata, and place it directly into my Artist - Album folder hierarchy, but you could probably get by with just setting this to your music library directly if you aren't in to that side of things. You can also set things like upload and queue limits and all that while in the preferences tab. Then just go to the "search files" tab and it's pretty easy to find what you want. I usually just go with "[album title] flac" and that's enough to get it 95% of the time even for obscure stuff. Pick an uploader based on speed / how nicely organized the files are, then just right click the folder name -> download folder and it will move over to the download tab.

Realized right after typing this out that there is a setup assistant at help -> setup assistant. Probably way more helpful than I am but feel free to ask anything else if you need to!