I have been map making for Red Orchestra 2 since August 2012. Basically I was a noobie just like you guys reading this. I didn't have any nice tutorials to read. My method of learning was going through the stock maps and reverse engineering what they did. I had some help from other veteran map makers and the UDK tutorials. It was very hard but I didn't give up and I was determined to make a map.
Recognize those two pictures up there? That was Winterwald when I first made it. I am sure many of you here have played it.
It looks much nicer after I spent many hours working on it. So don't give up guys! You can make amazing maps too.
There are a few important places you should go to to learn how to make maps.
You should register yourself to the official TWI forums. There is a mine of information on that forum. I used it quite often in my early days of map making.
Windows 7 64-bit 2.0+ GHz multi-core processor 8 GB System RAM NVIDIA 8000 series or higher graphics card Plenty of HDD space
If you have less memory then this, you WILL crash while using the content browser and scrolling around in it. It loads all that content as it comes into view. Now, this probably won't fix your issues with crashing if you are running out of memory while viewing assets in the generic browser. It'll probably only reduce how often it happens.
Installing the SDK
Open up the steam window.
At the top select View -> Tools.
Scroll down to Red Orchestra 2 SDK
Right click and install game
Map Makers Guild
I have set up a steam group for everyone who wants to be a map maker. Here you can meet other map makers and ask questions and find help for map making.