You really need to look at some literature on framing or watch some you tube vids. The header for a 3/0 door is 41". for 3/0 windows will be around 39" for the header. It looks to me like you have those studs laid out in that wall on 24" O.C. Stop right there and change your layout to 16" O.C. not that much more cost involved and will be much better to finish out I believe. It only takes 1/3 more materials to do that. Make sure your floor is square, if it's not you're going to have to lay it out square on the floor, finding a happy medium that will work with whatever floor you have. It can be done. If it were me and I've done a helluva lot of this I would build my two longest walls the length of the floor. Build them both the same length, just in case your floor isn't square like i said earlier. You probably need to find someone with some experience to help you at least to get started and on the right track. you can take the same material and build a pile of **** or something really nice, the only difference is knowing what you're doing.
I'm glad you're willing to tackle it without much or any experience but really, you do need to know a few things to do it and not waste your time and materials. (money).
Surely you know someone who can steer you in the right direction.
Good luck, you can do it, but take your time and know exactly what it is you're doing and why you're doing it.
I wish I were nearby, I'd be glad to get you started.
Again, Good Luck,
Stafford