Yes! I'm glad more people are getting into warframe...
Nothing in this game is explained well at all...
I'll try and sum a few things up, if there is anything else just ask, I'm still quite new so I don't know everything but I'm getting there...
-Weapon blueprints can be brought for credits from the store for credits.
- Better weapons, or more desirable weapons (prime weapons) are found in the void missions, usually on completion, if your lucky.
-Some blueprints are awarded from daily log in prizes, I have a gorgon blueprint which I found out is only available as a daily prize and is no longer available to buy.
-Warframe blueprints are usually found on completion of boss levels, with the exception of Oberon, I believe they can be found pretty much anywhere if your lucky, after completing a boss level, you get your prize of a helmet, systems or chassis blueprint.
- Each boss has a certain Warframe set of blueprints, E.G. Boss Alad V, has Valkyr helmet, chassis and systems blueprints, beat the level you get 1 of them, you can get duplicates so it may take up to around 10 completions to get all 3 parts...
Once all 3 parts are acquired, you can build them in foundry, providing you have the correct resources. After they are built, you need to head to the store and buy the relevant blueprint, then you may construct your new Warframe, it takes 72 hours.
-Prime warframe parts are also found on Void missions, with a very low chance of actually acquiring the parts...
-Void keys are missions just like regular missions but set in an Orokin tower, like a fancy palace. The enemy's are harder depending on if your key is a I, II, III. Keys are where the best items are acquired, keys are also 1 time completion, if you complete the mission and reap the rewards, your key is gone and you must acquire more... Fail and you may keep trying.
Keys can be given from alert missions, daily log ins, awards from missions or brought with platinum.
-Derelict keys are made in the foundry, and act the same as void keys, but different rewards, and the enemy's are the infested, and is set on a derelict ship so it's a lot more dark and gloomy. Derelict assassination keys and boss are the only place Nekros Warframe blueprints can be awarded.
Also, if you haven't already noticed, this game wants you to buy platinum, platinum can get you the best gear quickly, but anything you want is fully aquirable on your own without spending a penny. It just takes a lot of time...
Hope some of this helps!