How fast can You get big arms, and what to do? WORKOUT?

i take it you meant 160lbs there, well 3 weeks is a start and its good to see enthusiasm but if you really want to get toned and muscular then weight training is the way to go, work out what muscles you want to increase in m and research some exercises to do for those muscles and put together a weekly routine with those exercises, i am impressed with your diet change and hope you can keep it up, when i started lifting weights i found it hard to adjust to the new non deep fried everything diet but yeah protein is what you need for muscle. also if you want to get ripped and appear more muscular then i would recommend doing at least 30 minutes of cardio EVERY DAY not just the days you work out as this will reduce your fat, the weight training does nothing to reduce your fat. check out the website in my sources you should find all you need (it helped me a lot when i started out too) and if you want to ask anything else feel free to message me, i hope this can help