If you find your way blocked by a Laser Barrier, there is most likely one or more security cameras around that detected a hostile target.
Look for green (non hostile cameras) or red (hostile camera detecting your or your teammates) on the ceiling nearby and destroy them to shut down the barrier.
Tiplet: if you cannot find the security camera, move the whole team somewhere to try to get out of the camera’s detection. Then either make a dash for it or try to deduce where the cameras are.
Also, it is possible to bypass an active Laser Barrier by using some powers (from wiki: Excalibur‘s “Slash Dash,” Rhino‘s “Rhino Charge,” Loki‘s “Invisibility,” and Trinity‘s “Link“) or sometimes by sliding (though not very reliable for the beginner)
This is how it looks when it has not detected you:
When it has detected you it will glow red and follow your movement.
I don't recall how many Warframe and weapon slots you start with (I've bought several expansions for each), but here's how you can check how many you have of each:
edited for update 10 UI overhaul
In the upper right, pick the Arsenal button. Then pick the Inventory button (right above mods). By default you should now be looking at your Warframes; it will list each Warframe you have, its rank, how much it sells for (almost always 10k credits), and also any empty Warframe slots you have. If you look in the upper left of this display, the next button to the right of the Warframe selection is weapons. If you pick that all of your weapons will be listed, along with their ranks & sell values. As with Warframes, if you scroll to the end of this list it will tell you how many empty slots you have.
I think you start with 2 Warframe slots and 6(?) weapon slots.
Best Answer
With Update 9 a new intro/tutorial based on the E3 Trailer was added to the game and the option to replay it.
To replay the Tutorial open your profile page in game by pressing the xp/credits/platinum bar and you will now see a Tutorial button.