Well clearly you're ecto. You still are lean. Start out by bombarding your muscles for a week. Go heavy to shock them back into things. Prolly try a push/pull/legs routine. You have to break down to build. MAke sure you get enough carbs and protein. To start back into it try to stay with compound movements. Then work more on isolation around 2-3 week. Consistancy is key. Diet needs to be there too.
Pics too big