Maybe i could GM a shadowrun session or two...

[Madeiner]

... but i havent even played a session.

I have been mostly a D&D DM for so many years now, also having tried a few different systems.
Lately i have been thinking about trying Shadowrun even if i have little to no information about it. I have played the PC game Shadowrun returns and that's it.

I know there are many versions of Shadowrun RPG (up to fifth edition last year, i read)

I wanted to ask:

- how immediate is the rule system? I learn pretty fast, but i dont want to ask my players to read a manual for what is probably a session or two. I'd love to explain the rules as we play.
- which Shadowrun version should i use? I am looking for something that is easy to play, contained in one manual rather than many different volumes, possibly with website or SRD support for easy rules checking.
- are there many published adventures (or whatever the shadowrun term is)?
- where can i find the major differences in the various editions? I'd be inclined to start with the latest edition, except i keep thinking that if i was trying d&d knowing nothing and tried 4th edition, i probably would have abandoned d&d entirely.

[LibraryOgre]

- how immediate is the rule system? I learn pretty fast, but i dont want to ask my players to read a manual for what is probably a session or two. I'd love to explain the rules as we play.
- which Shadowrun version should i use? I am looking for something that is easy to play, contained in one manual rather than many different volumes, possibly with website or SRD support for easy rules checking.
- are there many published adventures (or whatever the shadowrun term is)?
- where can i find the major differences in the various editions? I'd be inclined to start with the latest edition, except i keep thinking that if i was trying d&d knowing nothing and tried 4th edition, i probably would have abandoned d&d entirely.

Given the first criteria, I would suggest the 4th edition. It works on the pretty standard "Stat+Skill" method of generating dice pools, so if they're used to games at all, it should be a snap. Generally, roll Stat+Skill and count up the number of 5s and 6s. There's more to the system than that, but it will carry you a long way.

[Thoa]

If you only want to try it out and don´t want to read an entire manual I would recommend the quickstart rules.
Here are these Rules for the 4th Edition.
http://www.shadowruntabletop.com/wp-content/uploads/Downloads/Shadowrun%20Quick-Start%20Rules.pdf

In the back is a short story adventure.
To just try it out, these Rules should be sufficient.

In SR the Basic rules are always in the Core Rulebook. These have around 400 Pages and as a DM you should read it all.

I can not recommend any Editions because so far I have only played 4th, but I am diving into the 5th Edition rules and I think they are also good.
4th and 5th edition are not so far away from each other. (In fact the Basics are the same)

I don´t think there is a SRD support for any SR rules.

There are plenty published Adventures, but I never played one of these.

[Zavoniki]

I've only played with 5th, but the basics are fairly easy. You roll stat + skill number of d6's and look for 5's and 6's, with each counting as a success. If you have more 1's than successes, you have a critical failure(called a critical glitch). Each roll normally has a limit associated with it, which is the maximum number of successes you can have with this roll.

It can get a lot more complicated(especially if you start looking into Magic and/or the Matrix), but the pure basics are very simple.