Firstly, welcome to Islam, you are now part of the beautiful community of Muslims, alhamdulillah.
Gaining knowledge is so important and a life-long effort, and I know from personal experience it can be quite bewildering on where to start.
I'd say learn about Tawhid, the oneness of Allah swt, and read the biography of the Prophet Muhammad (peace be upon him).
Then you could start with the six articles of faith, and learn about your primary duties detailed in the five pillars of Islam (atm I think salah would be important).
This is a wonderful website which has the core beliefs of Islam described and explained really well: http://www.islamreligion.com/
IslamicBoard isn't too bad either, lol, if you have any questions just ask inshaAllah.
http://www.islamiconlineuniversity.com has excellent, free courses for the new Muslim. I recommend taking the courses "The First Day" and "The First Week" before delving into anything more complicated.
welcome brother. Changing your religion to Islam from Atheism under your profile would be a good start
Joking aside, inshallah (God willing) you should focus on the basics and fundamentals of Islam. When Muslims tell you about Islam and it doesn't sound right, ask them for proof from the Quran and Sunnah of the Prophet. Many Muslims will tell you what they think is Islam, it isn't always right.
Get Minhaj Al Muslim book if you can, it's good on building foundational knowledge. You can also check this one out: