Hi Kristaps,
Welcome to the forum. You'll find that it can help you lots in many aspects. For one, you can get to know people connected to origami - which I think is really nice. But you can also get help on improving your origami skills. There's an own forum section devoted to answering questions on diagrams and crease patterns.
As to finding things to fold online, there are lots of resources there also:
Of course I'll have to name my website first, which features instructional videos, some downloadable diagrams, and a gallery which usually lists where diagrams for the models can be found. Check it out at
http://www.happyfolding.com
You can also search the origami database
http://www.origamidatabase.com/ and search for models there. If you restrict your search to web content, then chances are you'll immediately have diagrams that are available online. [Sometimes the entries might be outdated, because some sites have disappeared.]
The site I started folding with is
http://www.origami.com or more specifically
http://www.origami.com/diagram.html - search for all models, and you'll see just how many diagrams are listed there.
If you like modular origami I'd recommend
http://origamee.net/ - in the left navigation bar there are links to "own" diagrams and "other" diagrams, which gives you a big fill of superb modular designs, all of which have diagrams online.
Now there's lots more diagrams online (the next two I'd probably list are
http://glynnorigami.co.uk/ and
http://origami.as/ ), but I think this should get you started and keep you busy for a bit.
As to working with crease patterns, I think it's better if you work on your folding skills first. Once those are up to par (which might take months, or years - really depends), you can start exploring crease patterns. I think there are a couple of guides on how to fold from crease patterns online (e.g.
http://spinflipper.com/origami/cp/ ). In any case, it will be harder than folding from diagrams, so my suggestion is to take it slow.
Best wishes, happy folding, and especially welcome,
-- Sara
Edit: By the way, if you've caught the origami bug, then you'll likely want to start buying books sometime in the future. Lots of superb designs are diagrammed in books, and I think buying those books is not only the way to get those diagrams, but also to show your appreciation to the designers. I started by searching the web for free diagrams, too, but have built up a small collection of origami books by now.
