How to find maps with in-game Google search

I've been using Roll20 for 3 years, but given the highly visual interface, I feel like battle maps are under-utilized. The marketplace has many great maps (I've bought many Sci-Fi packs for Warhammer 40k since it's nearly impossible to find non-Star Wars futuristic maps), but they're still missing many great classics or maps from WOTC's website, or just around the web. Uploading is always a great option, but I can barely get my players together twice a month to play, so I can't justify paying for membership, and 100mb is pretty small when I have over 7.5gb of maps saved to my PC. The last choice is using the built-in Google-like feature, but to a novice it seems pretty awful. Is there a trick to it that I don't understand? I could upload my own music to soundcloud and I found it easily enough through the in-game Jukebox, but I never seem to find anything by the in-game Google feature, even searching 'everything' and using the same term I used on real google. Is there something I'm missing?

I'll admit I never used most of these tutorials, but that's only because this website is so intuitive that most of it seemed redundant. I don't think there was a tutorial for this specific problem. I scoured 13 pages of user questions and couldn't find any like mine, so I hope it wasn't answered yet. I don't want to create clutter, I just want to know if there is a guide to finding exactly what you want through the in-game browser, or if there are ways to give yourself maps without using your 100mb limit. Something like uploading them to Imgur, or Image Shack (I hate that place) or even RPGmapshare. I feel like I'm missing something so I might as well ask the experts!

Timothy, the in-game search "From The Web" is somewhat limited and won't pick up everything that can be found in Google. A tip or technique is to try different search words, search terms; and to use "Everything" on the drop-down setting as you are already doing. Any of those maps "From The Web" as well as any Purchases of maps from the Roll20 Marketplace, do not use up from your 100MB quota.

The 100MB on the free account will fit lots of large maps (or other graphics). Upload the ones that you need for the next game session. If you fill it up, you can delete some of your past maps (previously used, or unused) to free up space for new maps. 100MB is much more than would be normally used in a week or a month of gaming, even if your group managed to cross or play-across a dozen large maps. You can wait and decide to upgrade to the Roll20 Subscription accounts (more space) or if you want to delete old material to free space for uploading new material at that point. 

Wiki docs for your Art Library and free'ing up space,
https://wiki.roll20.net/Art_Library#Your_Quota

You should make sure the maps you upload are converted to JPEG with suitable resolution to keep the size down. For example, I convert maps for my 13th Age Alliance games from the PDF to JPEG at 72 dpi and they look fine at 18 units by 25 units and 100% zoom. 

I guess I just got nervous when I saw my library hit 51mb. It set off my adventurer, pack-hoarder mentality. Using the in-browser search feature requires an expansive vocabulary, but I've already improved my library of saved maps. At first I thought organization would be impossible without folders, but tags work even better.

As much as I love high quality maps, I can easily manage to scale a lot of them down, so that way I can always upload one or two in a pinch and delete them afterward.

Thank you for the advice!